Do not ignore all .mli files in texvccheck

The pattern "*.mli" was incorrectly added to texvccheck/.gitignore by
4c9dc2f08e with the comment "Compiled
source".  As with d9a7da14f1, .mli files
define the interfaces for the corresponding .ml module and thus should
not be ignored.

The only exception to this is parser.mli which is generated by the
ocamlyacc from the parser.mly definition, so this change only ignores
those files.

Change-Id: I263df70e58fb14a7228c32d5c985ff7f1b841891

math/.gitignore

@@ -2,6 +2,7 @@
 *.cmi
 *.cmx
 *.o
+parser.mli
 
 # The binaries
 texvc

texvccheck/.gitignore

@@ -1,9 +1,8 @@
 # Compiled source
-*.mli
-!tex.mli
 *.cmi
 *.cmx
 *.o
+parser.mli
 
 # The binaries
 texvccheck