git-p4: fix keyword-expansion regex

This text:

     my $dir = $File::Find::dir;
     return if ($dir !~ m,$options->{dirpat}$,);

was improperly converted to:

     my $dir = $File$dir !~ m,$options->{dirpat}$,);

by the keyword identifier expansion code.  Add a \n
to make sure the regex doesn't go across end-of-line
boundaries.
Signed-off-by: NPete Wyckoff <pw@padd.com>
Acked-by: NSimon Hausmann <simon@lst.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

contrib/fast-import/git-p4

@@ -963,7 +963,7 @@ class P4Sync(Command):
             if stat['type'] in ('text+ko', 'unicode+ko', 'binary+ko'):
                 text = re.sub(r'(?i)\$(Id|Header):[^$]*\$',r'$\1$', text)
             elif stat['type'] in ('text+k', 'ktext', 'kxtext', 'unicode+k', 'binary+k'):
-                text = re.sub(r'\$(Id|Header|Author|Date|DateTime|Change|File|Revision):[^$]*\$',r'$\1$', text)
+                text = re.sub(r'\$(Id|Header|Author|Date|DateTime|Change|File|Revision):[^$\n]*\$',r'$\1$', text)
 
             contents[stat['depotFile']] = text