Compile with -fno-common
https://github.com/ggreer/the_silver_searcher/commit/21eaa1c4160b868b0c5bbf59da17974429f30055

Index: src/ignore.h
--- src/ignore.h.orig
+++ src/ignore.h
@@ -29,7 +29,7 @@ struct ignores {
 };
 typedef struct ignores ignores;
 
-ignores *root_ignores;
+extern ignores *root_ignores;
 
 extern const char *evil_hardcoded_ignore_files[];
 extern const char *ignore_pattern_files[];
