Windows: Implement support for SRWLock shared

Exclusive was already implemented.

Source/Windows/Common/WinAPI/Sync.cpp

@@ -28,6 +28,18 @@ void ReleaseSRWLockExclusive(PSRWLOCK SRWLock) {
   RtlReleaseSRWLockExclusive(SRWLock);
 }
 
+void AcquireSRWLockShared(PSRWLOCK SRWLock) {
+  RtlAcquireSRWLockShared(SRWLock);
+}
+
+void ReleaseSRWLockShared(PSRWLOCK SRWLock) {
+  RtlReleaseSRWLockShared(SRWLock);
+}
+
+DLLEXPORT_FUNC(BOOLEAN, TryAcquireSRWLockShared, (PSRWLOCK SRWLock)) {
+  return RtlTryAcquireSRWLockShared(SRWLock);
+}
+
 DLLEXPORT_FUNC(BOOLEAN, TryAcquireSRWLockExclusive, (PSRWLOCK SRWLock)) {
   return RtlTryAcquireSRWLockExclusive(SRWLock);
 }

Source/Windows/include/winternl.h

@@ -540,6 +540,9 @@ NTSTATUS WINAPI RtlWow64SetThreadContext(HANDLE, const WOW64_CONTEXT*);
 void WINAPI Wow64ProcessPendingCrossProcessItems(void);
 NTSTATUS WINAPI Wow64SystemServiceEx(UINT, UINT*);
 NTSTATUS WINAPI RtlWow64SuspendThread(HANDLE, ULONG*);
+void WINAPI RtlAcquireSRWLockShared(RTL_SRWLOCK*);
+void WINAPI RtlReleaseSRWLockShared(RTL_SRWLOCK*);
+BOOLEAN WINAPI RtlTryAcquireSRWLockShared(RTL_SRWLOCK*);
 
 #ifdef __cplusplus
 }