configure: add fallback when checking for ar

racket/src/configure

@@ -672,6 +672,7 @@ EXEEXT
 OBJEXT
 CPP
 RANLIB
+platform_ar_found
 STRIP
 GREP
 EGREP
@@ -3848,6 +3849,47 @@ fi
 
 if test "$AR" = '' ; then
   AR="${ac_tool_prefix}ar"
+  # Extract the first word of "$AR", so it can be a program name with args.
+set dummy $AR; ac_word=$2
+{ echo "$as_me:$LINENO: checking for $ac_word" >&5
+echo $ECHO_N "checking for $ac_word... $ECHO_C" >&6; }
+if test "${ac_cv_prog_platform_ar_found+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  if test -n "$platform_ar_found"; then
+  ac_cv_prog_platform_ar_found="$platform_ar_found" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+  for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_platform_ar_found="yes"
+    echo "$as_me:$LINENO: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+done
+IFS=$as_save_IFS
+
+  test -z "$ac_cv_prog_platform_ar_found" && ac_cv_prog_platform_ar_found="no"
+fi
+fi
+platform_ar_found=$ac_cv_prog_platform_ar_found
+if test -n "$platform_ar_found"; then
+  { echo "$as_me:$LINENO: result: $platform_ar_found" >&5
+echo "${ECHO_T}$platform_ar_found" >&6; }
+else
+  { echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+fi
+
+
+  if test "$platform_ar_found" = 'no' ; then
+    AR="ar"
+  fi
 fi
 if test "$ARFLAGS" = '' ; then
   ARFLAGS=ruv
@@ -10040,6 +10082,7 @@ EXEEXT!$EXEEXT$ac_delim
 OBJEXT!$OBJEXT$ac_delim
 CPP!$CPP$ac_delim
 RANLIB!$RANLIB$ac_delim
+platform_ar_found!$platform_ar_found$ac_delim
 STRIP!$STRIP$ac_delim
 GREP!$GREP$ac_delim
 EGREP!$EGREP$ac_delim
@@ -10078,7 +10121,6 @@ EXTRA_GMP_DEP!$EXTRA_GMP_DEP$ac_delim
 OSX!$OSX$ac_delim
 NOT_OSX!$NOT_OSX$ac_delim
 MINGW!$MINGW$ac_delim
-NOT_MINGW!$NOT_MINGW$ac_delim
 _ACEOF
 
   if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 97; then
@@ -10120,6 +10162,7 @@ _ACEOF
 ac_delim='%!_!# '
 for ac_last_try in false false false false false :; do
   cat >conf$$subs.sed <<_ACEOF
+NOT_MINGW!$NOT_MINGW$ac_delim
 FRAMEWORK_INSTALL_DIR!$FRAMEWORK_INSTALL_DIR$ac_delim
 FRAMEWORK_REL_INSTALL!$FRAMEWORK_REL_INSTALL$ac_delim
 FRAMEWORK_PREFIX!$FRAMEWORK_PREFIX$ac_delim
@@ -10182,7 +10225,7 @@ LIBOBJS!$LIBOBJS$ac_delim
 LTLIBOBJS!$LTLIBOBJS$ac_delim
 _ACEOF
 
-  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 60; then
+  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 61; then
     break
   elif $ac_last_try; then
     { { echo "$as_me:$LINENO: error: could not make $CONFIG_STATUS" >&5

racket/src/racket/configure.ac

@@ -484,6 +484,10 @@ fi
 AC_PROG_RANLIB
 if test "$AR" = '' ; then 
   AR="${ac_tool_prefix}ar"
+  AC_CHECK_PROG(platform_ar_found, $AR, yes, no)
+  if test "$platform_ar_found" = 'no' ; then
+    AR="ar"
+  fi
 fi
 if test "$ARFLAGS" = '' ; then 
   ARFLAGS=ruv