Add .git to the list

This commit was SVN r21870.

contrib/hg/build-hgignore.pl

@@ -15,7 +15,7 @@ die "Not in HG+SVN repository top dir"
 
 # Put in some specials that we ignore everywhere
 my @hgignore;
-push(@hgignore, "# Automatically generated file; edits may be lost!
+push(@hgignore, "# Automatically generated by build-hgignore.pl; edits may be lost!
 syntax: glob");
 my @globals = qw/.libs
 .deps
@@ -30,6 +30,7 @@ my @globals = qw/.libs
 *.S
 *.loT
 .DS_Store
+.git*
 stamp-h[1-9]
 configure
 config.guess