100mA
  #   ˆl–Ü4ý(©v( 
û½pM)‹FÿÁ„_i¯ÃÄ .¨    # lib-prefix.m4 serial 17
dnl Copyright (C) 2001-2005, 2008-2020 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

dnl From Bruno Haible.

dnl AC_LIB_PREFIX adds to the CPPFLAGS and LDFLAGS the flags that are needed
dnl to access previously installed libraries. The basic assumption is that
dnl a user will want packages to use other packages he previously installed
dnl with the same --prefix option.
dnl This macro is not needed if only AC_LIB_LINKFLAGS is used to locate
dnl libraries, but is otherwise very convenient.
AC_DEFUN([AC_LIB_PREFIX],
[
  AC_BEFORE([$0], [AC_LIB_LINKFLAGS])
  AC_REQUIRE([AC_PROG_CC])
  AC_REQUIRE([AC_CANONICAL_HOST])
  AC_REQUIRE([AC_LIB_PREPARE_MULTILIB])
  AC_REQUIRE([AC_LIB_PREPARE_PREFIX])
  dnl By default, look in $includedir and $libdir.
  use_additional=yes
  AC_LIB_WITH_FINAL_PREFIX([
    eval additional_includedir=\"$includedir\"
    eval additional_libdir=\"$libdir\"
  ])
  AC_ARG_WITH([lib-prefix],
[[  --with-lib-prefix[=DIR] search for libraries in DIR/include and DIR/lib
  --without-lib-prefix    don't search for libraries in includedir and libdir]],
[
    if test "X$withval" = "Xno"; then
      use_additional=no
    else
      if test "X$withval" = "X"; then
        AC_LIB_WITH_FINAL_PREFIX([
          eval additional_includedir=\"$includedir\"
          eval additional_libdir=\"$libdir\"
        ])
      else
        additional_includedir="$withval/include"
        additional_libdir="$withval/$acl_libdirstem"
      fi
    fi
])
  if test $use_additional = yes; then
    dnl Potentially add $additional_includedir to $CPPFLAGS.
    dnl But don't add it
    dnl   1. if it's the standard /usr/include,
    dnl   2. if it's already present in $CPPFLAGS,
    dnl   3. if it's /usr/local/include and we are using GCC on Linux,
    dnl   4. if it doesn't exist as a directory.
    if test "X$additional_includedir" != "X/usr/include"; then
      haveit=
      for x in $CPPFLAGS; do
        AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
        if test "X$x" = "X-I$additional_includedir"; then
          haveit=yes
          break
        fi
      done
      if test -z "$haveit"; then
        if test "X$additional_includedir" = "X/usr/local/include"; then
          if test -n "$GCC"; then
            case $host_os in
              linux* | gnu* | k*bsd*-gnu) haveit=yes;;
            esac
          fi
        fi
        if test -z "$haveit"; then
          if test -d "$additional_includedir"; then
            dnl Really add $additional_includedir to $CPPFLAGS.
            CPPFLAGS="${CPPFLAGS}${CPPFLAGS:+ }-I$additional_includedir"
          fi
        fi
      fi
    fi
    dnl Potentially add $additional_libdir to $LDFLAGS.
    dnl But don't add it
    dnl   1. if it's the standard /usr/lib,
    dnl   2. if it's already present in $LDFLAGS,
    dnl   3. if it's /usr/local/lib and we are using GCC on Linux,
    dnl   4. if it doesn't exist as a directory.
    if test "X$additional_libdir" != "X/usr/$acl_libdirstem"; then
      haveit=
      for x in $LDFLAGS; do
        AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
        if test "X$x" = "X-L$additional_libdir"; then
          haveit=yes
          break
        fi
      done
      if test -z "$haveit"; then
        if test "X$additional_libdir" = "X/usr/local/$acl_libdirstem"; then
          if test -n "$GCC"; then
            case $host_os in
              linux*) haveit=yes;;
            esac
          fi
        fi
        if test -z "$haveit"; then
          if test -d "$additional_libdir"; then
            dnl Really add $additional_libdir to $LDFLAGS.
            LDFLAGS="${LDFLAGS}${LDFLAGS:+ }-L$additional_libdir"
          fi
        fi
      fi
    fi
  fi
])

dnl AC_LIB_PREPARE_PREFIX creates variables acl_final_prefix,
dnl acl_final_exec_prefix, containing the values to which $prefix and
dnl $exec_prefix will exp