fix win_compile script

a typo slept through code review

Change-Id: I880f8b99bf7c05f01e6ef4310931fcf6e0811f67
Reviewed-by: Anthony Léonard <anthony.leonard@savoirfairelinux.com>

scripts/win_compile.sh

@@ -4,8 +4,7 @@ rootdir=$(pwd)
 HOST=i686-w64-mingw32
 ARCH=32
 CMAKE_TOOLCHAIN_FILE=$rootdir/lrc/cmake/winBuild.cmake
-$CORES=${CORES:=`nproc --all`}
-echo "running compilation on $CORES threads"
+echo "running compilation on ${CORES:=`nproc --all`} threads"
 
 while test -n "$1"
 do