Fix compilation errors for std=c++2a

Author: mixern6

public/mathlib/mathlib.h

@@ -329,7 +329,7 @@ void inline SinCos( float radians, float *sine, float *cosine )
 		fstp DWORD PTR [eax]
 	}
 #elif defined( GNUC )
-	register double __cosr, __sinr;
+	double __cosr, __sinr;
  	__asm __volatile__ ("fsincos" : "=t" (__cosr), "=u" (__sinr) : "0" (radians));
 
   	*sine = __sinr;
@@ -629,11 +629,6 @@ template <class T> FORCEINLINE T AVG(T a, T b)
 // XYZ macro, for printf type functions - ex printf("%f %f %f",XYZ(myvector));
 #define XYZ(v) (v).x,(v).y,(v).z
 
-//
-// Returns a clamped value in the range [min, max].
-//
-#define clamp(val, min, max) (((val) > (max)) ? (max) : (((val) < (min)) ? (min) : (val)))
-
 inline float Sign( float x )
 {
 	return fsel( x, 1.0f, -1.0f ); // x >= 0 ? 1.0f : -1.0f

public/tier0/threadtools.h

@@ -683,7 +683,7 @@ class CThreadFastMutex
 			return false;
 
 		ThreadMemoryBarrier();
-		++m_depth;
+		m_depth = m_depth + 1;
 		return true;
 	}
 
@@ -744,7 +744,7 @@ class CThreadFastMutex
 			DebuggerBreak();
 #endif
 
-		--m_depth;
+		m_depth = m_depth - 1;
 		if ( !m_depth )
 		{
 			ThreadMemoryBarrier();