odintrin.h: reduce scope of floating-point OD_LOG2

Move it entenc.c, its only user.
Otherwise, it brings floating point functions into the namespace of
the decoder, while math.h isn't stricly needed to use odintrin.h.

Change-Id: I97f19d9768be4b2921b09c4d96bc4a1239faa945

aom_dsp/entenc.c

diff --git a/aom_dsp/entenc.c b/aom_dsp/entenc.c
index ad147a1..0d69148 100644
--- a/aom_dsp/entenc.c
+++ b/aom_dsp/entenc.c
@@ -15,9 +15,17 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <math.h>
 #include "aom_dsp/entenc.h"
 #include "aom_dsp/prob.h"
 
+#if OD_MEASURE_EC_OVERHEAD
+#if !defined(M_LOG2E)
+#define M_LOG2E (1.4426950408889634073599246810019)
+#endif
+#define OD_LOG2(x) (M_LOG2E * log(x))
+#endif  // OD_MEASURE_EC_OVERHEAD
+
 /*A range encoder.
   See entdec.c and the references for implementation details \cite{Mar79,MNW98}.
 

av1/common/odintrin.h

diff --git a/av1/common/odintrin.h b/av1/common/odintrin.h
index a555265..e75148f 100644
--- a/av1/common/odintrin.h
+++ b/av1/common/odintrin.h
@@ -14,10 +14,6 @@
 #ifndef AV1_COMMON_ODINTRIN_H_
 #define AV1_COMMON_ODINTRIN_H_
 
-#if defined(_MSC_VER)
-# define _USE_MATH_DEFINES
-#endif
-#include <math.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -30,26 +26,6 @@
 extern "C" {
 #endif
 
-# if !defined(M_PI)
-#  define M_PI      (3.1415926535897932384626433832795)
-# endif
-
-# if !defined(M_SQRT2)
-#  define M_SQRT2 (1.41421356237309504880168872420970)
-# endif
-
-# if !defined(M_SQRT1_2)
-#  define M_SQRT1_2 (0.70710678118654752440084436210485)
-# endif
-
-# if !defined(M_LOG2E)
-#  define M_LOG2E (1.4426950408889634073599246810019)
-# endif
-
-# if !defined(M_LN2)
-#  define M_LN2 (0.69314718055994530941723212145818)
-# endif
-
 typedef int od_coeff;
 
 #define OD_DIVU_DMAX (1024)
@@ -74,9 +50,6 @@
 #define OD_CLZ(x) (-get_msb(x))
 #define OD_ILOG_NZ(x) (OD_CLZ0 - OD_CLZ(x))
 
-#define OD_LOG2(x) (M_LOG2E*log(x))
-#define OD_EXP2(x) (exp(M_LN2*(x)))
-
 /*Enable special features for gcc and compatible compilers.*/
 #if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
 #define OD_GNUC_PREREQ(maj, min, pat)                                \