Fix ccache being silently bypassed on iOS builds

Xcode does not export user-defined build settings as environment
variables for invoked scripts, so the CCACHE_BINARY value set on
the project by react_native_post_install never reached
ccache-clang.sh / ccache-clang++.sh. Because the original
exec command collapsed an empty $CCACHE_BINARY, builds silently
invoked clang directly and ccache was never used.

Fall back to a PATH lookup when CCACHE_BINARY is unset, and only
prepend ccache when an executable is actually available so projects
without ccache still build.

Fixes #55381

Author: wildan-m

packages/react-native/scripts/xcode/ccache-clang++.sh

@@ -11,4 +11,13 @@ REACT_NATIVE_CCACHE_CONFIGPATH=$SCRIPT_DIR/ccache.conf
 # Provide our config file if none is already provided
 export CCACHE_CONFIGPATH="${CCACHE_CONFIGPATH:-$REACT_NATIVE_CCACHE_CONFIGPATH}"
 
-exec $CCACHE_BINARY clang++ "$@"
+# Xcode does not export user-defined build settings as environment variables
+# for invoked scripts, so $CCACHE_BINARY may be empty even when set in the
+# project. Fall back to a PATH lookup so ccache is still used.
+CCACHE_BINARY="${CCACHE_BINARY:-$(command -v ccache)}"
+
+if [ -n "$CCACHE_BINARY" ]; then
+    exec "$CCACHE_BINARY" clang++ "$@"
+fi
+
+exec clang++ "$@"

packages/react-native/scripts/xcode/ccache-clang.sh

@@ -11,4 +11,13 @@ REACT_NATIVE_CCACHE_CONFIGPATH=$SCRIPT_DIR/ccache.conf
 # Provide our config file if none is already provided
 export CCACHE_CONFIGPATH="${CCACHE_CONFIGPATH:-$REACT_NATIVE_CCACHE_CONFIGPATH}"
 
-exec $CCACHE_BINARY clang "$@"
+# Xcode does not export user-defined build settings as environment variables
+# for invoked scripts, so $CCACHE_BINARY may be empty even when set in the
+# project. Fall back to a PATH lookup so ccache is still used.
+CCACHE_BINARY="${CCACHE_BINARY:-$(command -v ccache)}"
+
+if [ -n "$CCACHE_BINARY" ]; then
+    exec "$CCACHE_BINARY" clang "$@"
+fi
+
+exec clang "$@"