Bug Fix: Update compiler version check rule

Double brackets are required the the reg approach.
Otherwise the check will always return false.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: Id2e23180f8578a407cc8fc977dc810fa9945ed62
diff --git a/run-build.sh b/run-build.sh
index 9c2d2f5..20f602b 100755
--- a/run-build.sh
+++ b/run-build.sh
@@ -33,7 +33,7 @@
 compiler_path="${COMPILER_VERSION}_PATH"
 export PATH=$PATH:"${!compiler_path}"
 # Show compiler version
-if [ $COMPILER_VERSION =~ "ARMCLANG" ] ; then
+if [[ $COMPILER_VERSION =~ "ARMCLANG" ]] ; then
     armclang --version
 else
     arm-none-eabi-gcc --version