versioncmp.h: move declarations for versioncmp.c functions from cache.h

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -648,6 +648,4 @@ int stat_validity_check(struct stat_validity *sv, const char *path);
  */
 void stat_validity_update(struct stat_validity *sv, int fd);
 
-int versioncmp(const char *s1, const char *s2);
-
 #endif /* CACHE_H */

ref-filter.c

@@ -19,6 +19,7 @@
 #include "revision.h"
 #include "utf8.h"
 #include "version.h"
+#include "versioncmp.h"
 #include "trailer.h"
 #include "wt-status.h"
 #include "commit-slab.h"

versioncmp.c

@@ -1,6 +1,7 @@
-#include "cache.h"
+#include "git-compat-util.h"
 #include "config.h"
 #include "string-list.h"
+#include "versioncmp.h"
 
 /*
  * versioncmp(): copied from string/strverscmp.c in glibc commit

versioncmp.h

@@ -0,0 +1,6 @@
+#ifndef VERSIONCMP_H
+#define VERSIONCMP_H
+
+int versioncmp(const char *s1, const char *s2);
+
+#endif /* VERSIONCMP_H */