[Linux] Change from using /tmp to /dev/shm in MemArena so we don't ca…

…use any disk IO, also unlink file while it is open to allow multiple instances running. This was discussed months ago, but was never implemented for whatever reason.

Source/Core/Common/Src/MemArena.cpp

@@ -30,7 +30,7 @@
 #endif
 
 #ifndef _WIN32
-static const char* ram_temp_file = "/tmp/gc_mem.tmp";
+static const char* ram_temp_file = "/dev/shm/gc_mem.tmp";
 #endif
 
 void MemArena::GrabLowMemSpace(size_t size)
@@ -40,6 +40,7 @@ void MemArena::GrabLowMemSpace(size_t size)
 #else
 	mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
 	fd = open(ram_temp_file, O_RDWR | O_CREAT, mode);
+	unlink(ram_temp_file);
 	ftruncate(fd, size);
 	return;
 #endif
@@ -53,7 +54,6 @@ void MemArena::ReleaseSpace()
 	hMemoryMapping = 0;
 #else
 	close(fd);
-	unlink(ram_temp_file);
 #endif
 }