submodule, path: extract slash conversion

Extract the backslash-to-slash conversion into a helper function.

src/path.c

@@ -1671,3 +1671,19 @@ bool git_path_isvalid(
 
 	return verify_component(repo, start, (c - start), flags);
 }
+
+int git_path_normalize_slashes(git_buf *out, const char *path)
+{
+	int error;
+	char *p;
+
+	if ((error = git_buf_puts(out, path)) < 0)
+		return error;
+
+	for (p = out->ptr; *p; p++) {
+		if (*p == '\\')
+			*p = '/';
+	}
+
+	return 0;
+}

src/path.h

@@ -591,4 +591,9 @@ extern bool git_path_isvalid(
 	const char *path,
 	unsigned int flags);
 
+/**
+ * Convert any backslashes into slashes
+ */
+int git_path_normalize_slashes(git_buf *out, const char *path);
+
 #endif

src/submodule.c

@@ -787,19 +787,15 @@ int git_submodule_resolve_url(git_buf *out, git_repository *repo, const char *ur
 
 	git_buf_sanitize(out);
 
+	/* We do this in all platforms in case someone on Windows created the .gitmodules */
 	if (strchr(url, '\\')) {
-		char *p;
-		if ((error = git_buf_puts(&normalized, url)) < 0)
+		if ((error = git_path_normalize_slashes(&normalized, url)) < 0)
 			return error;
 
-		for (p = normalized.ptr; *p; p++) {
-			if (*p == '\\')
-				*p = '/';
-		}
-
 		url = normalized.ptr;
 	}
 
+
 	if (git_path_is_relative(url)) {
 		if (!(error = get_url_base(out, repo)))
 			error = git_path_apply_relative(out, url);