Introduce a generic clamp function to clean up some similarly duplicated code.

Source/Core/Core/HW/StreamADPCM.cpp

@@ -5,6 +5,7 @@
 // Adapted from in_cube by hcs & destop
 
 #include "StreamADPCM.h"
+#include "MathUtil.h"
 
 // STATE_TO_SAVE (not saved yet!)
 static s32 histl1;
@@ -31,8 +32,7 @@ s16 ADPDecodeSample(s32 bits, s32 q, s32& hist1, s32& hist2)
 		break;
 	}
 	hist = (hist + 0x20) >> 6;
-	if (hist >  0x1fffff) hist =  0x1fffff;
-	if (hist < -0x200000) hist = -0x200000;
+	MathUtil::Clamp(hist, -0x200000, 0x1fffff);
 
 	s32 cur = (((s16)(bits << 12) >> (q & 0xf)) << 6) + hist;
 
@@ -40,9 +40,7 @@ s16 ADPDecodeSample(s32 bits, s32 q, s32& hist1, s32& hist2)
 	hist1 = cur;
 
 	cur >>= 6;
-
-	if (cur < -0x8000) return -0x8000;
-	if (cur >  0x7fff) return  0x7fff;
+	MathUtil::Clamp(cur, -0x8000, 0x7fff);
 
 	return (s16)cur;
 }