Specialize fdlibm to jerry

Keep IEEE code paths only:
* removed SVID, XOPEN, POSIX code paths from everywhere.
* deleted s_lib_version.c, as version is only useful if multiple
  standards are supported.
* deleted k_standard.c, as it handles non-IEEE exception cases only.
* renamed the e_{acos,asin,atan2,exp,fmod,log,pow,sqrt}.c sources as
  s_.*, dropped the __ieee754_ prefix from the names of the
  appropriate functions therein, and deleted the
  w_{acos,asin,atan2,exp,fmod,log,pow,sqrt}.c wrapper code.

Keep C99 declaration variants only:
* removed old C-style function declaration variants.
* removed data declaration variants where const qualifier was not
  used.

Clean unused sources/functions:
* removed s_{rint,significand,tanh}.c and the appropriate functions
  defined therein.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

third-party/fdlibm/s_fabs.c

@@ -17,12 +17,7 @@
 
 #include "fdlibm.h"
 
-#ifdef __STDC__
-	double fabs(double x)
-#else
-	double fabs(x)
-	double x;
-#endif
+double fabs(double x)
 {
 	__HI(x) &= 0x7fffffff;
         return x;