Adding ChibiOS path override feature to chbuild.sh

tools/chbuild.sh

@@ -11,7 +11,6 @@ JOBS=$(grep -c ^processor /proc/cpuinfo)
 SKIP_ARRAY=(Win32)
 RETCODE=0
 
-
 function test_skip {
     Array=$1
     SKIP=0
@@ -42,7 +41,11 @@ function chbuild {
     fi
     pushd $t > /dev/null
     printf "BUILDING: ${t}\n"
-    make --quiet -j $JOBS > /dev/null
+    if [ -z "$CH_PATH" ]; then
+        make --quiet -j $JOBS > /dev/null
+    else
+        make CHIBIOS=$CH_PATH --quiet -j $JOBS > /dev/null
+    fi
     if [ $? -ne 0 ]; then
       ((NOK++))
       FAIL+=($t)