update libwebp build.sh

scripts/libwebp/build.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+export CC=${FAM_CC}
+
+./configure \
+    --prefix=${INSTALL_DIR} \
+    --host=${TARGET} \
+    --with-sysroot=${SYSROOT_PATH} \
+    --target=${TARGET} || exit 1
+
+${MAKE_EXECUTABLE} clean
+${MAKE_EXECUTABLE} -j${HOST_NPROC}
+${MAKE_EXECUTABLE} install