# ---------------------------------------------------------------------------
# Provide various compatibility macros for older Autoconf machines
# Definitions were copied from the Autoconf source code.
# ---------------------------------------------------------------------------
m4_ifdef([AS_VAR_IF],,m4_define([AS_VAR_IF],
[AS_LITERAL_WORD_IF([$1],
  [AS_IF(m4_ifval([$2], [[test "x$$1" = x[]$2]], [[${$1:+false} :]])],
  [AS_VAR_COPY([as_val], [$1])
   AS_IF(m4_ifval([$2], [[test "x$as_val" = x[]$2]], [[${as_val:+false} :]])],
  [AS_IF(m4_ifval([$2],
    [[eval test \"x\$"$1"\" = x"_AS_ESCAPE([$2], [`], [\"$])"]],
    [[eval \${$1:+false} :]])]),
[$3], [$4])]))dnl