vcs-svn: use strstr instead of memmem

memmem is a GNU extension.

Avoiding it makes the code clearer and makes it easier for projects
that don't share git's compat/ code, such as the standalone
svn-dump-fast-export project, to reuse the vcs-svn/ library.

Signed-off-by: David Barr <davidbarr@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

vcs-svn/fast_export.c

@@ -158,7 +158,7 @@ static int parse_cat_response_line(const char *header, off_t *len)
 
 	if (ends_with(header, headerlen, " missing"))
 		return error("cat-blob reports missing blob: %s", header);
-	type = memmem(header, headerlen, " blob ", strlen(" blob "));
+	type = strstr(header, " blob ");
 	if (!type)
 		return error("cat-blob header has wrong object type: %s", header);
 	n = strtoumax(type + strlen(" blob "), (char **) &end, 10);