wrappers: Don't rely on "readlink -f"

Older macOS versions (macOS 12.2 at least) don't support this
option, while newer macOS versions do support it (macOS 12.6).

The solution is based on https://stackoverflow.com/a/1116890/3115956,
but simplified for this usecase.

wrappers/clang-target-wrapper.sh

@@ -14,7 +14,17 @@
 # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
-DIR="$(cd "$(dirname $(readlink -f "$0"))" && pwd)"
+get_dir() {
+    target="$1"
+    while [ -L "$target" ]; do
+        cd "$(dirname "$target")"
+        target="$(readlink "$(basename "$target")")"
+    done
+    cd "$(dirname "$target")"
+    pwd
+}
+
+DIR="$(get_dir "$0")"
 BASENAME="$(basename "$0")"
 TARGET="${BASENAME%-*}"
 EXE="${BASENAME##*-}"

wrappers/ld-wrapper.sh

@@ -14,7 +14,17 @@
 # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
-DIR="$(cd "$(dirname $(readlink -f "$0"))" && pwd)"
+get_dir() {
+    target="$1"
+    while [ -L "$target" ]; do
+        cd "$(dirname "$target")"
+        target="$(readlink "$(basename "$target")")"
+    done
+    cd "$(dirname "$target")"
+    pwd
+}
+
+DIR="$(get_dir "$0")"
 export PATH="$DIR":"$PATH"
 
 BASENAME="$(basename "$0")"

wrappers/objdump-wrapper.sh

@@ -14,7 +14,17 @@
 # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
-DIR="$(cd "$(dirname $(readlink -f "$0"))" && pwd)"
+get_dir() {
+    target="$1"
+    while [ -L "$target" ]; do
+        cd "$(dirname "$target")"
+        target="$(readlink "$(basename "$target")")"
+    done
+    cd "$(dirname "$target")"
+    pwd
+}
+
+DIR="$(get_dir "$0")"
 export PATH="$DIR":"$PATH"
 
 if [ "$1" = "-f" ]; then