fixup .gitignore to include other necessary debian files

filesystem/packages/font-source-code-pro/.gitignore

@@ -3,7 +3,12 @@ src/debian/*
 !src/debian/compat
 !src/debian/changelog
 !src/debian/control
+!src/debian/copyright
 !src/debian/rules
+!src/debian/install
+!src/debian/postinst
+!src/debian/source
+
 
 #generic packaging artifacts
 debhelper-build-stamp
@@ -16,4 +21,4 @@ debhelper-build-stamp
 *.log
 *.substvars
 *.diff.gz
-*.upload
+*.upload