flame@yamato snips % net-snmp-config --cflags -march=barcelona -O2 -pipe -Wformat=2 -Wno-error -Wno-pointer-sign -g -ggdb -Wstrict-aliasing=2 -Wno-format-zero-length -Ulinux -Dlinux=linux -I. -I/usr/include flame@yamato snips % net-snmp-config --base-cflags -march=barcelona -O2 -pipe -Wformat=2 -Wno-error -Wno-pointer-sign -g -ggdb -Wstrict-aliasing=2 -Wno-format-zero-length -Ulinux -Dlinux=linux -I/usr/include flame@yamato snips % net-snmp-config --ldflags -Wl,-O1 -Wl,--as-needed -Wl,--hash-style=gnu -Wl,--sort-common by the way, -Ulinux -Dlinux=linux breaks the default preprocessor macros defined by gcc ....
Fixed in 5.4.2.1-r3.