[libc][NFC] Remove all trailing spaces from libc (#82831)

Summary:
There are a lot of random training spaces on various lines. This patch
just got rid of all of them with `sed 's/\ \+$//g'.

libc/include/fcntl.h.def

@@ -14,4 +14,4 @@
 
 %%public_api()
 
-#endif // LLVM_LIBC_FCNTL_H 
+#endif // LLVM_LIBC_FCNTL_H

libc/include/sched.h.def

@@ -14,4 +14,4 @@
 
 %%public_api()
 
-#endif // LLVM_LIBC_SCHED_H 
+#endif // LLVM_LIBC_SCHED_H

libc/include/spawn.h.def

@@ -13,4 +13,4 @@
 
 %%public_api()
 
-#endif // LLVM_LIBC_SPAWN_H 
+#endif // LLVM_LIBC_SPAWN_H