sv.c: Remove redundant PERL_ABS in S_hextract.

It seems redundant to take the absolute value of the first argument
of frexp() here, because the sign of the first argument will only affect
its return value which is discarded in this case.

Author: t-a-k

sv.c

@@ -11735,7 +11735,7 @@ S_hextract(pTHX_ const NV nv, int* exponent, bool *subnormal,
     assert(HEXTRACTSIZE <= VHEX_SIZE);
 
     PERL_UNUSED_VAR(ix); /* might happen */
-    (void)Perl_frexp(PERL_ABS(nv), exponent);
+    (void)Perl_frexp(nv, exponent);
     *subnormal = FALSE;
     if (vend && (vend <= vhex || vend > vmaxend)) {
         /* diag_listed_as: Hexadecimal float: internal error (%s) */