Port SkUtils opts to SkOpts.

include/core/SkFloatingPoint.h

Index: include/core/SkFloatingPoint.h
diff --git a/include/core/SkFloatingPoint.h b/include/core/SkFloatingPoint.h
index 5ca4d103d0bf160ff103812dc25b64b317f9c0c2..2ca1d088d391341eaf1d652353a084a0da7049ba 100644
--- a/include/core/SkFloatingPoint.h
+++ b/include/core/SkFloatingPoint.h
@@ -11,6 +11,7 @@
 #define SkFloatingPoint_DEFINED
 
 #include "SkTypes.h"
+#include "../private/SkOpts.h"
 
 #include <math.h>
 #include <float.h>
@@ -127,8 +128,6 @@ extern const uint32_t gIEEENegativeInfinity;
 #define SK_FloatInfinity            (*SkTCast<const float*>(&gIEEEInfinity))
 #define SK_FloatNegativeInfinity    (*SkTCast<const float*>(&gIEEENegativeInfinity))
 
-namespace SkOpts { extern float (*rsqrt)(float); }
-
 // Fast, approximate inverse square root.
 // Compare to name-brand "1.0f / sk_float_sqrt(x)".  Should be around 10x faster on SSE, 2x on NEON.
 static inline float sk_float_rsqrt(const float x) {