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.
+*htmlrecode-1.3.0-r1 (19 Nov 2010)
+ 19 Nov 2010; Sebastian Pipping <email@example.com>
+ Support user's CXXFLAGS (bug #240135) and LDFLAGS (bug #336551)