MdePkg: Apply uncrustify changes

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3737

Apply uncrustify changes to .c/.h files in the MdePkg package

Cc: Andrew Fish <afish@apple.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

MdePkg/Library/BaseStackCheckLib/BaseStackCheckNull.c

@@ -6,4 +6,4 @@
 
 **/
 
-extern int __BaseStackCheckNull;
+extern int  __BaseStackCheckNull;