Upgrade mtools to 3.0.37

This version contains a fix for -Wstring-concatenation error.

Test: presubmit
Bug: 175068488
Change-Id: Id4f2ae49da91a481ab2625fdf17668689b640794
diff --git a/dirCache.h b/dirCache.h
index 04f9f3e..161c9a5 100644
--- a/dirCache.h
+++ b/dirCache.h
@@ -45,9 +45,9 @@
 			      wchar_t *longName, wchar_t *shortName,
 			      struct directory *dir);
 void freeDirCache(Stream_t *Stream);
-dirCacheEntry_t *addFreeEntry(dirCache_t *Stream, 
+dirCacheEntry_t *addFreeEntry(dirCache_t *Stream,
 			      unsigned int begin, unsigned int end);
-dirCacheEntry_t *addFreeEndEntry(dirCache_t *Stream, 
+dirCacheEntry_t *addFreeEndEntry(dirCache_t *Stream,
 				 unsigned int begin, unsigned int end,
 				 int isAtEnd);
 dirCacheEntry_t *addEndEntry(dirCache_t *Stream, unsigned int pos);