do_cmake.sh: fix syntax for /bin/sh (doesn't have +=)

Signed-off-by: Dan Mick <dan.mick@redhat.com>

diff --git a/do_cmake.sh b/do_cmake.sh
index 9b04cb114f6eecdf5fb24ea243261301cdc177ab..739da8e5b0ce322426f9e1bac9389bb074f16187 100755 (executable)
--- a/do_cmake.sh
+++ b/do_cmake.sh
@@ -8,7 +8,7 @@ fi
 ARGS=""
 if which ccache ; then
     echo "enabling ccache"
-    ARGS+="-DWITH_CCACHE=ON"
+    ARGS="$ARGS -DWITH_CCACHE=ON"
 fi
 
 mkdir build