Syscalls: Prefix _ to shm syscall names to avoid namespace conflict

Termux uses defines for these, so our token pasting fails, but we also
still want to use their define so we can fall down their emulation
library whenever possible.

Prefix an underscore to be able to use both our number definitions and
their defines in the same file.

Scripts/GenerateSyscallNumbers.py

@@ -59,7 +59,13 @@ SyscallArm64File = "/include/uapi/asm-generic/unistd.h"
 DefinitionRenameDict = {
     "pread64": "pread_64",
     "pwrite64": "pwrite_64",
-    "prlimit64": "prlimit_64"
+    "prlimit64": "prlimit_64",
+    # Shm symbols conflict with termux defines and FEX's syscall token pasting.
+    # Underscore at the start to avoid name collision
+    "shmget": "_shmget",
+    "shmctl": "_shmctl",
+    "shmat": "_shmat",
+    "shmdt": "_shmdt",
 }
 
 Definitions_x64 = []