libm: remove unused includes

src/libm/s_isinf.c

diff --git a/src/libm/s_isinf.c b/src/libm/s_isinf.c
index 9486b05..5b496cf 100644
--- a/src/libm/s_isinf.c
+++ b/src/libm/s_isinf.c
@@ -10,7 +10,6 @@
  * no branching!
  */
 
-#include "math.h"
 #include "math_private.h"
 
 int __isinf(double x)

src/libm/s_isinff.c

diff --git a/src/libm/s_isinff.c b/src/libm/s_isinff.c
index 184c9aa..8462f76 100644
--- a/src/libm/s_isinff.c
+++ b/src/libm/s_isinff.c
@@ -9,7 +9,6 @@
  * no branching!
  */
 
-#include "math.h"
 #include "math_private.h"
 
 int __isinff (float x)

src/libm/s_isnan.c

diff --git a/src/libm/s_isnan.c b/src/libm/s_isnan.c
index 4831086..b863470 100644
--- a/src/libm/s_isnan.c
+++ b/src/libm/s_isnan.c
@@ -15,7 +15,6 @@
  * no branching!
  */
 
-#include "math.h"
 #include "math_private.h"
 
 int __isnan(double x)

src/libm/s_isnanf.c

diff --git a/src/libm/s_isnanf.c b/src/libm/s_isnanf.c
index 1cb308c..19dc2c5 100644
--- a/src/libm/s_isnanf.c
+++ b/src/libm/s_isnanf.c
@@ -19,7 +19,6 @@
  * no branching!
  */
 
-#include "math.h"
 #include "math_private.h"
 
 int __isnanf(float x)

src/libm/s_scalbn.c

diff --git a/src/libm/s_scalbn.c b/src/libm/s_scalbn.c
index 799e7fc..11808b2 100644
--- a/src/libm/s_scalbn.c
+++ b/src/libm/s_scalbn.c
@@ -19,7 +19,6 @@
 
 #include "math_libm.h"
 #include "math_private.h"
-#include <limits.h>
 
 static const double
 two54  = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */