Gentoo's Bugzilla –
Attachment 846322 Details for
Bug 889078app-text/crengine-ng-0.9.3 fails to compile (CLANG-STRICTER-SYSTEM): fonts.c:945:7: error: call to undeclared function strcasecmp; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]