IVGCVSW-8168 Fix errors while using build tool for android target

* Add Android compiler flag
* Install llvm package for docker compilation

Signed-off-by: Nikhil Raj <nikhil.raj@arm.com>
Change-Id: I9054b64e372fe9d9181d9b2321be86b3f3d95267
diff --git a/build-tool/scripts/common.sh b/build-tool/scripts/common.sh
index d966a35..419d278 100755
--- a/build-tool/scripts/common.sh
+++ b/build-tool/scripts/common.sh
@@ -45,8 +45,8 @@
 # ANDROID
 ANDROID_API_VERSION=30
 ANDROID_ARM_ARCH="arm64-v8a"
-ANDROID64_x86_TOOLCHAIN+="$NDK_SRC/toolchains/llvm/prebuilt/linux-x86_64"
-ANDROID64_COMPILER_FLAGS+="CC="$ANDROID64_x86_TOOLCHAIN"/bin/aarch64-linux-android"$ANDROID_API_VERSION"-clang \
+ANDROID64_x86_TOOLCHAIN="$NDK_SRC/toolchains/llvm/prebuilt/linux-x86_64/"
+ANDROID64_COMPILER_FLAGS="CC="$ANDROID64_x86_TOOLCHAIN"/bin/aarch64-linux-android"$ANDROID_API_VERSION"-clang \
                            CXX="$ANDROID64_x86_TOOLCHAIN"/bin/aarch64-linux-android"$ANDROID_API_VERSION"-clang++ "
 
 # Flatbuffers