patch 9.0.0880: preprocessor indenting is off

Problem:    Preprocessor indenting is off.
Solution:   Adjust preprocessor indentation. (Ken Takata, closes #11546)
diff --git a/src/if_perl.xs b/src/if_perl.xs
index 08e0e02..34315be 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -147,7 +147,7 @@
 
 // Suppress Infinite warnings when compiling XS modules under macOS 12 Monterey.
 #if defined(__clang__) && defined(__clang_major__) && __clang_major__ > 11
-#pragma clang diagnostic ignored "-Wcompound-token-split-by-macro"
+# pragma clang diagnostic ignored "-Wcompound-token-split-by-macro"
 #endif
 
 /* Compatibility hacks over */