[...]
i686-pc-linux-gnu-gcc -o .libs/scanimage scanimage.o stiff.o  ../lib/liblib.a ../backend/.libs/libsane.so -ldl /usr/lib/libusb.so -lpthread /usr/lib/libtiff.so /usr/lib/libjpeg.so -lz -lm -lc /usr/lib/libieee1284.so
i686-pc-linux-gnu-gcc -o .libs/saned saned.o  ../sanei/libsanei.a ../lib/liblib.a ../backend/.libs/libsane.so -ldl /usr/lib/libusb.so -lpthread /usr/lib/libtiff.so /usr/lib/libjpeg.so -lz -lm -lc /usr/lib/libieee1284.so
creating scanimage
creating saned
make[1]: Leaving directory `/var/tmp/portage/media-gfx/sane-backends-1.0.18-r2/work/sane-backends-1.0.18/frontend'
making all in tools
make[1]: Entering directory `/var/tmp/portage/media-gfx/sane-backends-1.0.18-r2/work/sane-backends-1.0.18/tools'
i686-pc-linux-gnu-gcc -c -O2 -march=pentium4 -pipe -W -Wall -DHAVE_CONFIG_H -I. -I. -I../include -I../include -D_REENTRANT -DPATH_SANE_CONFIG_DIR=/etc/sane.d          -DPATH_SANE_DATA_DIR=/usr/share         -DPATH_SANE_LOCK_DIR=           -DV_MAJOR=1 -DV_MINOR=0 sane-find-scanner.c
i686-pc-linux-gnu-gcc -c -O2 -march=pentium4 -pipe -W -Wall -DHAVE_CONFIG_H -I. -I. -I../include -I../include -D_REENTRANT -DPATH_SANE_CONFIG_DIR=/etc/sane.d          -DPATH_SANE_DATA_DIR=/usr/share         -DPATH_SANE_LOCK_DIR=           -DV_MAJOR=1 -DV_MINOR=0 check-usb-chip.c
sane-find-scanner.c:35:22: error: ddk/scsi.h: No such file or directory
sane-find-scanner.c:36:26: error: ddk/ntddscsi.h: No such file or directory
In file included from sane-find-scanner.c:46:
/usr/include/usb.h:161: error: expected identifier or '(' before 'struct'
/usr/include/usb.h:163: error: expected ';' before 'unsigned'
/usr/include/usb.h:316: error: expected '{' before ')' token
/usr/include/usb.h:316: error: two or more data types in declaration specifiers
/usr/include/usb.h:325: error: expected '{' before ',' token
/usr/include/usb.h:325: error: two or more data types in declaration specifiers
sane-find-scanner.c: In function 'check_libusb_device':
sane-find-scanner.c:540: error: expected identifier or '(' before 'struct'
sane-find-scanner.c:545: error: expected expression before 'struct'
sane-find-scanner.c:549: error: expected expression before 'struct'
sane-find-scanner.c:628: error: expected identifier before 'struct'
sane-find-scanner.c:631: error: expected identifier before 'struct'
sane-find-scanner.c: In function 'build_scsi_dev_list':
sane-find-scanner.c:735: error: 'PSCSI_ADAPTER_BUS_INFO' undeclared (first use in this function)
sane-find-scanner.c:735: error: (Each undeclared identifier is reported only once
sane-find-scanner.c:735: error: for each function it appears in.)
sane-find-scanner.c:735: error: expected ';' before 'adapter'
sane-find-scanner.c:736: error: 'PSCSI_INQUIRY_DATA' undeclared (first use in this function)
sane-find-scanner.c:736: error: expected ';' before 'inquiry'
sane-find-scanner.c:764: error: 'IOCTL_SCSI_GET_INQUIRY_DATA' undeclared (first use in this function)
sane-find-scanner.c:778: error: 'adapter' undeclared (first use in this function)
sane-find-scanner.c:778: error: expected ';' before 'buffer'
sane-find-scanner.c:793: error: invalid type argument of '->'
sane-find-scanner.c:794: error: invalid type argument of '->'
sane-find-scanner.c:795: error: invalid type argument of '->'
sane-find-scanner.c:797: error: invalid type argument of '->'
sane-find-scanner.c:797: error: invalid type argument of '->'
sane-find-scanner.c:797: error: invalid type argument of '->'
sane-find-scanner.c:802: error: invalid type argument of '->'
sane-find-scanner.c:807: error: invalid type argument of '->'
sane-find-scanner.c: In function 'parse_file':
sane-find-scanner.c:1045: error: expected identifier before 'struct'
sane-find-scanner.c:1060: error: expected identifier before 'struct'
sane-find-scanner.c:1063: error: expected identifier before 'struct'
sane-find-scanner.c:1066: error: expected identifier before 'struct'
sane-find-scanner.c:1071: error: expected identifier before 'struct'
sane-find-scanner.c:1073: error: expected identifier before 'struct'
sane-find-scanner.c:1077: error: expected identifier before 'struct'
sane-find-scanner.c:1079: error: expected identifier before 'struct'
sane-find-scanner.c:1082: error: expected identifier before 'struct'
sane-find-scanner.c:1085: error: expected identifier before 'struct'
sane-find-scanner.c:1088: error: expected identifier before 'struct'
sane-find-scanner.c:1094: error: expected identifier before 'struct'
sane-find-scanner.c:1097: error: expected identifier before 'struct'
sane-find-scanner.c:1100: error: expected identifier before 'struct'
sane-find-scanner.c:1103: error: expected identifier before 'struct'
sane-find-scanner.c: In function 'main':
sane-find-scanner.c:1182: warning: unused variable 'default_dev_list'
make[1]: *** [sane-find-scanner.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make[1]: Leaving directory `/var/tmp/portage/media-gfx/sane-backends-1.0.18-r2/work/sane-backends-1.0.18/tools'
make: *** [all-recursive] Error 1

!!! ERROR: media-gfx/sane-backends-1.0.18-r2 failed.
Call stack:
  ebuild.sh, line 1568:   Called dyn_compile
  ebuild.sh, line 937:   Called src_compile
  sane-backends-1.0.18-r2.ebuild, line 104:   Called die