Add tests for f32 literals

Author: nicoburns

bindgen-tests/tests/expectations/tests/infinite-macro.rs

@@ -0,0 +1,7 @@
+#define INFINITY (1.0f/0.0f)
+#define NEG_INFINITY (-1.0f/0.0f)
+#define NAN (0.0f/0.0f)
+
+static const float F32_INFINITY = 1.0f / 0.0f;
+static const float F32_NEG_INFINITY = -1.0f / 0.0f;
+static const float F32_NAN = 0.0f / 0.0f;