While having "-g" in CFLAGS, I wondered why curl disables debugging alltogether. Somehow curl replaces "-g" by "-g0". Here is an excerpt: libtool: compile: i686-pc-linux-gnu-gcc -DHAVE_CONFIG_H -I../include/curl -I../include -I../include -I../lib -I../lib -march=pentium4 -mtune=pentium4 -O2 -pipe -Wall -fstack-protector -g0 -Wno-system-headers -pthread -MT connect.lo -MD -MP -MF .deps/connect.Tpo -c connect.c -o connect.o >/dev/null 2>&1
Curl's configures script enables the generation of debug info only if "--enable-debug" was given. Unfortunately, this options also sets the DEBUGBUILD preprocessor symbol, and this runs against Gentoo's philosophy of having debug symbols ready independent from special debug builds (which are specifically controlled by passing the "debug" use flag to emerge or ebuild).
While a hasq is usually bad form, it might be valid in this case.
Fixed in 7.21.4