chore(build): Add missing macros from autoconf-archive

build-aux/ax_file_escapes.m4

@@ -0,0 +1,30 @@
+# ===========================================================================
+#     https://www.gnu.org/software/autoconf-archive/ax_file_escapes.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_FILE_ESCAPES
+#
+# DESCRIPTION
+#
+#   Writes the specified data to the specified file.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Tom Howard <[email protected]>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 8
+
+AC_DEFUN([AX_FILE_ESCAPES],[
+AX_DOLLAR="\$"
+AX_SRB="\\135"
+AX_SLB="\\133"
+AX_BS="\\\\"
+AX_DQ="\""
+])