Disable strict autoconf version check so we can autoreconf in nixpkgs.

diff --git a/config/override.m4 b/config/override.m4
index 8b954d3cb..60c4cfd12 100644
--- a/config/override.m4
+++ b/config/override.m4
@@ -44,7 +44,6 @@ AC_DEFUN([_GCC_AUTOCONF_VERSION_CHECK],
   [m4_fatal([Please use exactly Autoconf ]_GCC_AUTOCONF_VERSION[ instead of ]m4_defn([m4_PACKAGE_VERSION])[.])])
 ])
 m4_define([AC_INIT], m4_defn([AC_INIT])[
-_GCC_AUTOCONF_VERSION_CHECK
 ])
 
 

This is needed for target linking to find e.g. crt0.o.
diff --git a/configure.ac b/configure.ac
index 05ddf6987..f5bbd5c72 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3166,7 +3166,7 @@ case " $target_configdirs " in
   *" --with-newlib "*)
    case "$target" in
     *-cygwin*)
-      FLAGS_FOR_TARGET=$FLAGS_FOR_TARGET' -L$$r/$(TARGET_SUBDIR)/winsup/cygwin -isystem $$s/winsup/cygwin/include'
+      FLAGS_FOR_TARGET=$FLAGS_FOR_TARGET' -B$$r/$(TARGET_SUBDIR)/winsup/cygwin -isystem $$s/winsup/cygwin/include'
       ;;
    esac
 

Autoconf clears EXEEXT= in cross, which breaks installation of utils/cygserver.

AC_CHECK_LIB is disabled in cross after AC_NO_EXECUTABLES.
diff --git a/winsup/configure.ac b/winsup/configure.ac
index e7ac814b1..14b56e130 100644
--- a/winsup/configure.ac
+++ b/winsup/configure.ac
@@ -40,6 +40,8 @@ AM_PROG_AS
 AC_LANG(C)
 AC_LANG(C++)
 
+EXEEXT=.exe
+
 AC_ARG_WITH([cross-bootstrap],[AS_HELP_STRING([--with-cross-bootstrap],[do not build programs using the MinGW toolchain or check for MinGW libraries (useful for bootstrapping a cross-compiler)])],[],[with_cross_bootstrap=no])
 
 AC_CYGWIN_INCLUDES
@@ -135,8 +137,6 @@ AM_CONDITIONAL(BUILD_DUMPER, [test "x$build_dumper" = "xyes"])
 # libbfd.a doesn't have a pkgconfig file, so we guess what it's dependencies
 # are, based on what's present in the build environment
 BFD_LIBS="-lintl -liconv -liberty -lz"
-AC_CHECK_LIB([sframe], [sframe_decode], [BFD_LIBS="${BFD_LIBS} -lsframe"])
-AC_CHECK_LIB([zstd], [ZSTD_isError], [BFD_LIBS="${BFD_LIBS} -lzstd"])
 AC_SUBST([BFD_LIBS])
 
 AC_CONFIG_FILES([