Restructure clang-target-wrapper.sh to set one flag per line

wrappers/clang-target-wrapper.sh

@@ -2,12 +2,20 @@
 DIR="$(cd "$(dirname "$0")" && pwd)"
 TARGET="$(basename $0 | sed 's/-[^-]*$//')"
 EXE=$(basename $0 | sed 's/.*-\([^-]*\)/\1/')
+ARCH=$(echo $TARGET | sed 's/-.*//')
+
+# Allow setting e.g. CCACHE=1 to wrap all building in ccache.
+if [ -n "$CCACHE" ]; then
+    CCACHE=ccache
+fi
+
+CLANG="$DIR/clang"
+FLAGS=""
 case $EXE in
 clang++|g++)
-    DRIVER_MODE=--driver-mode=g++
+    FLAGS="$FLAGS --driver-mode=g++"
     ;;
 esac
-ARCH=$(echo $TARGET | sed 's/-.*//')
 case $ARCH in
 i686)
     # Dwarf is the default for i686, but libunwind sometimes fails to
@@ -19,23 +27,24 @@ i686)
     # some handling relating to this dwarf opcode, which made
     # test/hello-exception.cpp work properly, but apparently there are
     # still issues with it).
-    ARCH_FLAGS=-fsjlj-exceptions
+    FLAGS="$FLAGS -fsjlj-exceptions"
     ;;
 x86_64)
     # SEH is the default here.
-    ARCH_FLAGS=
     ;;
 armv7)
     # Dwarf is the default here.
-    ARCH_FLAGS=
     ;;
 aarch64)
     # Dwarf is the default here.
-    ARCH_FLAGS=
     ;;
 esac
-# Allow setting e.g. CCACHE=1 to wrap all building in ccache.
-if [ -n "$CCACHE" ]; then
-    CCACHE=ccache
-fi
-$CCACHE $DIR/clang $DRIVER_MODE -target $TARGET -rtlib=compiler-rt -stdlib=libc++ -fuse-ld=lld -fuse-cxa-atexit $ARCH_FLAGS -Qunused-arguments "$@"
+
+FLAGS="$FLAGS -target $TARGET"
+FLAGS="$FLAGS -rtlib=compiler-rt"
+FLAGS="$FLAGS -stdlib=libc++"
+FLAGS="$FLAGS -fuse-ld=lld"
+FLAGS="$FLAGS -fuse-cxa-atexit"
+FLAGS="$FLAGS -Qunused-arguments"
+
+$CCACHE $CLANG $FLAGS "$@"