Configure Git whitespace size checks for .txt files

Restore size limit checks for .txt files.  Leave whitespace checks off
for .txt files other than CMakeLists.txt.

While at it, sort the order of patch file extensions in .gitattributes.

Change-Id: I0a64998cff1c04a7a701cccf493954f7af7bf68d
Merge "Configure Git whitespace size checks for .txt files"