termux_create_subpackages.sh: fix syntax errors

scripts/build/termux_create_subpackages.sh

@@ -71,11 +71,11 @@ termux_create_subpackages() {
 		local PKG_DEPS_SPC=" ${TERMUX_PKG_DEPENDS//,/} "
 
 		if [ -z "$TERMUX_SUBPKG_DEPEND_ON_PARENT" ] && [ "${PKG_DEPS_SPC/ $SUB_PKG_NAME /}" = "$PKG_DEPS_SPC" ]; then
-		    $TERMUX_SUBPKG_DEPENDS += ", $TERMUX_PKG_NAME (= $TERMUX_PKG_FULLVERSION)"
+		    TERMUX_SUBPKG_DEPENDS+=", $TERMUX_PKG_NAME (= $TERMUX_PKG_FULLVERSION)"
 		elif [ "$TERMUX_SUBPKG_DEPEND_ON_PARENT" = unversioned ]; then
-		    $TERMUX_SUBPKG_DEPENDS += ", $TERMUX_PKG_NAME"
+		    TERMUX_SUBPKG_DEPENDS+=", $TERMUX_PKG_NAME"
 		elif [ "$TERMUX_SUBPKG_DEPEND_ON_PARENT" = deps ]; then
-		    $TERMUX_SUBPKG_DEPENDS += ", $TERMUX_PKG_DEPENDS"
+		    TERMUX_SUBPKG_DEPENDS+=", $TERMUX_PKG_DEPENDS"
 		fi
 
 		test ! -z "$TERMUX_SUBPKG_DEPENDS" && echo "Depends: ${TERMUX_SUBPKG_DEPENDS/#, /}" >> control