fix warnings on Mac in src/effects

Fix these class of warnings:
- unused functions
- unused locals
- sign mismatch
- missing function prototypes
- missing newline at end of file
- 64 to 32 bit truncation

The changes prefer to link in dead code in the debug build
with 'if (false)' than to comment it out, but trivial cases
are commented out or sometimes deleted if it appears to be
a copy/paste error.
Review URL: https://codereview.appspot.com/6299049

git-svn-id: http://skia.googlecode.com/svn/trunk@4181 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkGradientShader.cpp b/src/effects/SkGradientShader.cpp
index 1ef6446..8203d60 100644
--- a/src/effects/SkGradientShader.cpp
+++ b/src/effects/SkGradientShader.cpp
@@ -2093,6 +2093,7 @@
     const SkPoint fCenter;
 };
 
+#ifndef SK_SCALAR_IS_FLOAT
 #ifdef COMPUTE_SWEEP_TABLE
 #define PI  3.14159265
 static bool gSweepTableReady;
@@ -2129,12 +2130,14 @@
 };
 static const uint8_t* build_sweep_table() { return gSweepTable; }
 #endif
+#endif
 
 // divide numer/denom, with a bias of 6bits. Assumes numer <= denom
 // and denom != 0. Since our table is 6bits big (+1), this is a nice fit.
 // Same as (but faster than) SkFixedDiv(numer, denom) >> 10
 
 //unsigned div_64(int numer, int denom);
+#ifndef SK_SCALAR_IS_FLOAT
 static unsigned div_64(int numer, int denom) {
     SkASSERT(numer <= denom);
     SkASSERT(numer > 0);
@@ -2201,8 +2204,10 @@
     }
     return result;
 }
+#endif
 
 // Given x,y in the first quadrant, return 0..63 for the angle [0..90]
+#ifndef SK_SCALAR_IS_FLOAT
 static unsigned atan_0_90(SkFixed y, SkFixed x) {
 #ifdef SK_DEBUG
     {
@@ -2256,6 +2261,7 @@
     SkASSERT(result <= 63);
     return result;
 }
+#endif
 
 //  returns angle in a circle [0..2PI) -> [0..255]
 #ifdef SK_SCALAR_IS_FLOAT