feat: add isnan and isfinite functions to webcc::math; update std namespace in compat/cmath

Author: io-eric

include/webcc/compat/cmath

@@ -13,6 +13,8 @@
 namespace std
 {
     using webcc::abs;
+    using webcc::isfinite;
+    using webcc::isnan;
     using webcc::sqrt;
     using webcc::sin;
     using webcc::cos;

include/webcc/core/math.h

@@ -61,6 +61,26 @@ namespace webcc
         return __builtin_nanf("");
     }
 
+    inline bool isnan(float x)
+    {
+        return __builtin_isnan(x);
+    }
+
+    inline bool isnan(double x)
+    {
+        return __builtin_isnan(x);
+    }
+
+    inline bool isfinite(float x)
+    {
+        return __builtin_isfinite(x);
+    }
+
+    inline bool isfinite(double x)
+    {
+        return __builtin_isfinite(x);
+    }
+
     // --- Linear Algebra ---
     struct Vec3
     {