devel/libstrfunc: fix build on GCC architectures

Needs new GCC:
sf_core/split.c: In function 'splitf':
sf_core/split.c:92: error: 'sed_t' undeclared (first use in this function)
sf_core/split.c:92: error: (Each undeclared identifier is reported only once
sf_core/split.c:92: error: for each function it appears in.)
sf_core/split.c:92: error: 'st' undeclared (first use in this function)

Approved by: mentors (implicit approval)