Gentoo's Bugzilla –
Attachment 342610 Details for
Bug 462276net-misc/curl-7.29.0-r1 on hardened with -D_FORTIFY_SOURCE in CFLAGS - configure: CFLAGS error: CFLAGS may only be used to specify C compiler flags, not macro definitions. Use CPPFLAGS for: -D_FORTIFY_SOURCE=2