build-package.sh: remove files .crates2.json from packages

.crates2.json is generated by cargo during the crate installation.

See https://github.com/termux/termux-packages/issues/5037.

scripts/build/termux_step_massage.sh

@@ -37,6 +37,10 @@ termux_step_massage() {
 			sed --follow-symlinks -i -E "1 s@^#\!(.*)/bin/(.*)@#\!$TERMUX_PREFIX/bin/\2@" "$file"
 	done < <(find -L . -type f -print0)
 
+	# Remove unneeded files created by rust/cargo.
+	rm -f .crates2.json
+
+	# Remove files specified in TERMUX_PKG_RM_AFTER_INSTALL.
 	test ! -z "$TERMUX_PKG_RM_AFTER_INSTALL" && rm -Rf $TERMUX_PKG_RM_AFTER_INSTALL
 
 	find . -type d -empty -delete # Remove empty directories