Break LCD and Bitmap text dependency on hardcoded atlas values

include/core/SkFloatingPoint.h

Index: include/core/SkFloatingPoint.h
diff --git a/include/core/SkFloatingPoint.h b/include/core/SkFloatingPoint.h
index 7427562323f39d3dfe22ea35b37c0c2a382cf0c9..f7ee816b12005a6377a34016e35f878696a1e270 100644
--- a/include/core/SkFloatingPoint.h
+++ b/include/core/SkFloatingPoint.h
@@ -158,4 +158,13 @@ static inline float sk_float_rsqrt(const float x) {
 #endif
 }
 
+// This is the number of significant digits we can print in a string such that when we read that
+// string back we get the floating point number we expect.  The minimum value C requires is 6, but
+// most compilers support 9
+#ifdef FLT_DECIMAL_DIG
+#define SK_FLT_DECIMAL_DIG FLT_DECIMAL_DIG
+#else
+#define SK_FLT_DECIMAL_DIG 9
+#endif
+
 #endif