c99_math: (trivial) implement exp2 for MSVC too

Unsurprisingly doesn't build otherwise with old msvc.

diff --git a/include/c99_math.h b/include/c99_math.h
index 0ca5a73..8a67fb1 100644 (file)
--- a/include/c99_math.h
+++ b/include/c99_math.h
@@ -146,6 +146,12 @@ exp2f(float f)
    return powf(2.0f, f);
 }
 
+static inline double
+exp2(double d)
+{
+   return pow(2.0, d);
+}
+
 #endif /* C99 */