libm/x86: use call instead of jump for wrappers

libm/x86: use call instead of jump for wrappers

GCC can emit prologue/epilogue code for the functions in various
different cases:
 - frame pointers
 - PIC build (to load ebx for indirect calls/jumps)
 - forced stack smashing protection

If we used jump in such cases, we'd corrupt the call stack and
crash.

Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>