BPMemory: Eliminate union type punning

This is undefined behavior in C++.

Source/Core/VideoCommon/BPMemory.cpp

@@ -4,6 +4,30 @@
 
 #include "VideoCommon/BPMemory.h"
 
+#include <cstring>
+
 // BP state
 // STATE_TO_SAVE
 BPMemory bpmem;
+
+float FogParam0::GetA() const
+{
+  // scale mantissa from 11 to 23 bits
+  const u32 integral = (static_cast<u32>(sign) << 31) | (static_cast<u32>(exponent) << 23) |
+                       (static_cast<u32>(mantissa) << 12);
+
+  float real;
+  std::memcpy(&real, &integral, sizeof(u32));
+  return real;
+}
+
+float FogParam3::GetC() const
+{
+  // scale mantissa from 11 to 23 bits
+  const u32 integral = (static_cast<u32>(c_sign) << 31) | (static_cast<u32>(c_exp) << 23) |
+                       (static_cast<u32>(c_mant) << 12);
+
+  float real;
+  std::memcpy(&real, &integral, sizeof(u32));
+  return real;
+}

Source/Core/VideoCommon/BPMemory.h

@@ -674,17 +674,7 @@ union FogParam0
     u32 sign : 1;
   };
 
-  float GetA()
-  {
-    union
-    {
-      u32 i;
-      float f;
-    } dummy;
-    dummy.i = ((u32)sign << 31) | ((u32)exponent << 23) |
-              ((u32)mantissa << 12);  // scale mantissa from 11 to 23 bits
-    return dummy.f;
-  }
+  float GetA() const;
 
   u32 hex;
 };
@@ -701,17 +691,7 @@ union FogParam3
   };
 
   // amount to subtract from eyespacez after range adjustment
-  float GetC()
-  {
-    union
-    {
-      u32 i;
-      float f;
-    } dummy;
-    dummy.i = ((u32)c_sign << 31) | ((u32)c_exp << 23) |
-              ((u32)c_mant << 12);  // scale mantissa from 11 to 23 bits
-    return dummy.f;
-  }
+  float GetC() const;
 
   u32 hex;
 };