gitignore: Actually pay attention to depends patches

There was a previous attempt to achieve this, and it was bad. This
works.

.gitignore

@@ -77,7 +77,7 @@ src/qt/bitcoin-qt.includes
 
 # Only ignore unexpected patches
 *.patch
-!depends/patches/*.patch
+!depends/patches/**/*.patch
 
 #libtool object files
 *.lo