I don't know the build system for this program (and this is a generic bug template so I cannot tell you which program exactly is), but my tests shows that it's not respecting CFLAGS properly.
Please look into it, since it's important to respect user CFLAGS.
+ 03 Jan 2009; Christoph Mende <email@example.com> txt2pdbdoc-1.4.4.ebuild:
+ Prevent automatic autotools rebuilding (bug 226433) and respect CFLAGS
+ (bug 240145)