Make jgit.sh work on windows when JGIT_CLASSPATH is set

jgit.sh was concatenating classpath entries with ":". On Windows systems
using "Git for Windows" this caused problems when JGIT_CLASSPATH was set.

Find out whether we are running on a platform which name starts with
"MINGW" ("Git for Windows" sets this) and use ";" as classpath
separator in this case.

Change-Id: I7e8fc2bee6513f587612accfc456a83d6277ef4a

org.eclipse.jgit.pgm/jgit.sh

@@ -61,14 +61,18 @@ this_script=`which "$0" 2>/dev/null`
 [ $? -gt 0 -a -f "$0" ] && this_script="$0"
 cp=$this_script
 
+platform="`uname`"
 if [ -n "$JGIT_CLASSPATH" ]
 then
-	cp="$cp:$JGIT_CLASSPATH"
+	cp_sep=:
+	# On Windows & MingW use ";" to separate classpath entries
+	[ "${platform#MINGW}" != "$platform" ] && cp_sep=";"
+	cp="$cp$cp_sep$JGIT_CLASSPATH"
 fi
 
 # Cleanup paths for Cygwin.
 #
-case "`uname`" in
+case "$platform" in
 CYGWIN*)
 	cp=`cygpath --windows --mixed --path "$cp"`
 	;;