Cleanup log2() portability checks

cmake/os/WindowsCache.cmake

@@ -87,7 +87,6 @@ SET(HAVE_LDIV 1 CACHE  INTERNAL "")
 SET(HAVE_LIMITS_H 1 CACHE  INTERNAL "")
 SET(HAVE_LOCALE_H 1 CACHE  INTERNAL "")
 SET(HAVE_LOCALTIME_R 1 CACHE  INTERNAL "")
-#SET(HAVE_LOG2 CACHE  INTERNAL "")
 SET(HAVE_LRAND48 CACHE  INTERNAL "")
 SET(HAVE_LSTAT CACHE  INTERNAL "")
 SET(HAVE_MADVISE CACHE  INTERNAL "")

config.h.cmake

@@ -165,7 +165,6 @@
 #cmakedefine HAVE_LDIV 1
 #cmakedefine HAVE_LRAND48 1
 #cmakedefine HAVE_LOCALTIME_R 1
-#cmakedefine HAVE_LOG2 1
 #cmakedefine HAVE_LSTAT 1
 #cmakedefine HAVE_MEMALIGN 1
 /* #cmakedefine HAVE_MLOCK 1 see Bug#54662 */

configure.cmake

@@ -477,8 +477,6 @@ CHECK_SYMBOL_EXISTS(TIOCSTAT "sys/ioctl.h" TIOCSTAT_IN_SYS_IOCTL)
 CHECK_SYMBOL_EXISTS(FIONREAD "sys/filio.h" FIONREAD_IN_SYS_FILIO)
 CHECK_SYMBOL_EXISTS(gettimeofday "sys/time.h" HAVE_GETTIMEOFDAY)
 
-CHECK_SYMBOL_EXISTS(log2  math.h HAVE_LOG2)
-
 #
 # Test for endianness
 #

include/my_global.h

@@ -843,17 +843,6 @@ inline unsigned long long my_double2ulonglong(double d)
 #define M_LN2 0.69314718055994530942
 #endif
 
-#ifndef HAVE_LOG2
-/*
-  This will be slightly slower and perhaps a tiny bit less accurate than
-  doing it the IEEE754 way but log2() should be available on C99 systems.
-*/
-static inline double log2(double x)
-{
-  return (log(x) / M_LN2);
-}
-#endif
-
 /*
   Max size that must be added to a so that we know Size to make
   addressable obj.