Make MatrixToFloat and Vector3ToFloat reentrant

Besides making it thread-safe, it suppresses a GCC warning
when making them static inline in an upcoming patch.

src/raylib.h

@@ -338,6 +338,14 @@ typedef struct Matrix {
     float m3, m7, m11, m15;
 } Matrix;
 
+typedef struct Float3 {
+    float f[3];
+} Float3;
+
+typedef struct Float16 {
+    float f[16];
+} Float16;
+
 // Color type, RGBA (32bit)
 typedef struct Color {
     unsigned char r;
@@ -743,11 +751,17 @@ RLAPI Color GetColor(int hexValue);                               // Returns a C
 RLAPI Color Fade(Color color, float alpha);                       // Color fade-in or fade-out, alpha goes from 0.0f to 1.0f
 
 // Math useful functions (available from raymath.h)
-RLAPI float *Vector3ToFloat(Vector3 vec);                         // Returns Vector3 as float array
-RLAPI float *MatrixToFloat(Matrix mat);                           // Returns Matrix as float array
 RLAPI Vector3 Vector3Zero(void);                                  // Vector with components value 0.0f
 RLAPI Vector3 Vector3One(void);                                   // Vector with components value 1.0f
 RLAPI Matrix MatrixIdentity(void);                                // Returns identity matrix
+#ifndef Vector3ToFloat
+#define Vector3ToFloat(vec) (Vector3ToFloat_(vec).f)              // Returns Vector3 as float array
+RLAPI Float3 Vector3ToFloat_(Vector3 vec);                        // don't use, use above
+#endif
+#ifndef MatrixToFloat
+#define MatrixToFloat(mat) (MatrixToFloat_(mat).f)                // Returns Matrix as float array
+RLAPI Float16 MatrixToFloat_(Matrix mat);                         // don't use, use above
+#endif
 
 // Misc. functions
 RLAPI void ShowLogo(void);                                        // Activate raylib logo at startup (can be done with flags)