[PATCH v2] Add missing HAVE_LLVM define to fix build with latest llvm

Broken since r314111

V2: pointed out by Jan Vesely
   - Use format() instead of % formating

Signed-off-by: Pavel Ondračka <pavel.ondracka@gmail.com>

Broken since r314111

V2: pointed out by Jan Vesely
   - Use format() instead of % formating

Signed-off-by: Pavel Ondračka <pavel.ondracka@gmail.com>

Reviewed-by: Jan Vesely <jan.vesely@rutgers.edu>

do you need someone to push this?

Jan