Enclosed functions in fenv.h with __BEGIN_DECLS/__END_DECLS

Those are C funcitons

Related CL: https://android-review.googlesource.com/#/c/41833/

Change-Id: I4386bcf948ad31c3690c9b7a145103088133d041
diff --git a/libm/arm/fenv.h b/libm/arm/fenv.h
index 893a596..534b12c 100644
--- a/libm/arm/fenv.h
+++ b/libm/arm/fenv.h
@@ -31,6 +31,8 @@
 
 #include <sys/types.h>
 
+__BEGIN_DECLS
+
 typedef	uint32_t	fenv_t;
 typedef	uint32_t	fexcept_t;
 
@@ -50,7 +52,6 @@
 #define	FE_DOWNWARD	0x0003
 #define	_ROUND_MASK	(FE_TONEAREST | FE_DOWNWARD | \
 			 FE_UPWARD | FE_TOWARDZERO)
-/* __BEGIN_DECLS */
 
 /* Default floating-point environment */
 extern const fenv_t	__fe_dfl_env;
@@ -212,6 +213,6 @@
 
 #endif /* __BSD_VISIBLE */
 
-/* __END_DECLS */
+__END_DECLS
 
 #endif	/* !_FENV_H_ */