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/mips/fenv.h b/libm/mips/fenv.h
index 061a696..583d002 100644
--- a/libm/mips/fenv.h
+++ b/libm/mips/fenv.h
@@ -29,8 +29,11 @@
 #ifndef	_FENV_H_
 #define	_FENV_H_
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 
+__BEGIN_DECLS
+
 typedef	__uint32_t	fenv_t;
 typedef	__uint32_t	fexcept_t;
 
@@ -50,7 +53,6 @@
 #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;
@@ -212,7 +214,7 @@
 
 #endif /* __BSD_VISIBLE */
 
-/* __END_DECLS */
+__END_DECLS
 
 #endif	/* !_FENV_H_ */