Make msys.bat work with WINE

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

msys.bat

@@ -47,7 +47,7 @@ if NOT "x%DISPLAY%" == "x" set DISPLAY=
 rem We here assume old behavior, to make sure that older platforms can still use
 rem this batch file to start their MSys environment.
 set BIN=""
-if EXIST bin\nul set BIN="bin\"
+if EXIST bin\nul set BIN=bin\
 if EXIST %BIN%bash.exe goto startbash
 if EXIST %BIN%rxvt.exe goto startrxvt