Allow multiple -m options to git-commit.

I find it very convenient to be able to supply multiple paragraphs
of text on the command line with a single git-commit call.  This
change permits multiple -m/--message type options to be supplied
to git-commit with each message being added as its own paragraph
of text in the commit message.

The -m option is still not permitted with -c/-C/-F nor are multiple
occurrences of these options permitted.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-commit.sh

@@ -260,20 +260,41 @@ do
   -m|--m|--me|--mes|--mess|--messa|--messag|--message)
       case "$#" in 1) usage ;; esac
       shift
-      log_given=t$log_given
+      log_given=m$log_given
+      if test "$log_message" = ''
+      then
           log_message="$1"
+      else
+          log_message="$log_message
+
+$1"
+      fi
       no_edit=t
       shift
       ;;
   -m*)
-      log_given=t$log_given
+      log_given=m$log_given
+      if test "$log_message" = ''
+      then
           log_message=`expr "$1" : '-m\(.*\)'`
+      else
+          log_message="$log_message
+
+`expr "$1" : '-m\(.*\)'`"
+      fi
       no_edit=t
       shift
       ;;
   --m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
-      log_given=t$log_given
+      log_given=m$log_given
+      if test "$log_message" = ''
+      then
           log_message=`expr "$1" : '-[^=]*=\(.*\)'`
+      else
+          log_message="$log_message
+
+`expr "$1" : '-[^=]*=\(.*\)'`"
+      fi
       no_edit=t
       shift
       ;;
@@ -378,7 +399,9 @@ esac
 
 case "$log_given" in
 tt*)
-  die "Only one of -c/-C/-F/-m can be used." ;;
+  die "Only one of -c/-C/-F can be used." ;;
+*tm*|*mt*)
+  die "Option -m cannot be combined with -c/-C/-F." ;;
 esac
 
 case "$#,$also,$only,$amend" in