Common: Move FPU-related helpers into Common namespace

Makes these utilities' namespace consistent with the majority of the
Common library.

Source/Core/Common/ArmFPURoundMode.cpp

@@ -11,6 +11,8 @@
 #include "Common/CommonTypes.h"
 #include "Common/Logging/Log.h"
 
+namespace Common::FPU
+{
 static u64 GetFPCR()
 {
 #ifdef _MSC_VER
@@ -31,8 +33,6 @@ static void SetFPCR(u64 fpcr)
 #endif
 }
 
-namespace FPURoundMode
-{
 static const u64 default_fpcr = GetFPCR();
 static u64 saved_fpcr = default_fpcr;
 
@@ -87,4 +87,4 @@ void LoadDefaultSIMDState()
   SetFPCR(default_fpcr);
 }
 
-}  // namespace FPURoundMode
+}  // namespace Common::FPU

Source/Core/Common/FPURoundMode.h

@@ -5,7 +5,7 @@
 
 #include "Common/CommonTypes.h"
 
-namespace FPURoundMode
+namespace Common::FPU
 {
 enum RoundMode : u32
 {
@@ -27,4 +27,4 @@ void SetSIMDMode(RoundMode rounding_mode, bool non_ieee_mode);
 void SaveSIMDState();
 void LoadSIMDState();
 void LoadDefaultSIMDState();
-}  // namespace FPURoundMode
+}  // namespace Common::FPU

Source/Core/Common/GenericFPURoundMode.cpp

@@ -6,7 +6,7 @@
 #include "Common/CommonTypes.h"
 
 // Generic, do nothing
-namespace FPURoundMode
+namespace Common::FPU
 {
 void SetSIMDMode(RoundMode rounding_mode, bool non_ieee_mode)
 {
@@ -20,4 +20,4 @@ void LoadSIMDState()
 void LoadDefaultSIMDState()
 {
 }
-}  // namespace FPURoundMode
+}  // namespace Common::FPU

Source/Core/Common/x64FPURoundMode.cpp

@@ -9,7 +9,7 @@
 #include "Common/CommonTypes.h"
 #include "Common/Intrinsics.h"
 
-namespace FPURoundMode
+namespace Common::FPU
 {
 // Get the default SSE states here.
 static u32 saved_sse_state = _mm_getcsr();
@@ -49,4 +49,4 @@ void LoadDefaultSIMDState()
 {
   _mm_setcsr(default_sse_state);
 }
-}  // namespace FPURoundMode
+}  // namespace Common::FPU