autotools, libtool, win32: add 'aarch64' support to the file magic test.

From libtool development commit 1638a6407573b74517b57a0f6e596918344a4394

Author: sezero

acinclude/libtool.m4

@@ -3033,7 +3033,7 @@ mingw* | pw32*)
     lt_cv_deplibs_check_method='file_magic ^x86 archive import|^x86 DLL'
     lt_cv_file_magic_cmd='func_win32_libid'
   else
-    lt_cv_deplibs_check_method='file_magic file format (pei*-i386(.*architecture: i386)?|pe-arm-wince|pe-x86-64)'
+    lt_cv_deplibs_check_method='file_magic file format (pei*-i386(.*architecture: i386)?|pe-arm-wince|pe-x86-64|pe-aarch64)'
     lt_cv_file_magic_cmd='$OBJDUMP -f'
   fi
   lt_cv_deplibs_check_method=pass_all

build-scripts/ltmain.sh

@@ -2568,7 +2568,7 @@ func_win32_libid ()
     ;;
   *ar\ archive*) # could be an import, or static
     if eval $OBJDUMP -f $1 | $SED -e '10q' 2>/dev/null |
-       $EGREP 'file format (pei*-i386(.*architecture: i386)?|pe-arm-wince|pe-x86-64)' >/dev/null ; then
+       $EGREP 'file format (pei*-i386(.*architecture: i386)?|pe-arm-wince|pe-x86-64|pe-aarch64)' >/dev/null ; then
       win32_nmres=`eval $NM -f posix -A $1 |
 	$SED -n -e '
 	    1,100{

configure

@@ -5385,7 +5385,7 @@ mingw* | pw32*)
     lt_cv_deplibs_check_method='file_magic ^x86 archive import|^x86 DLL'
     lt_cv_file_magic_cmd='func_win32_libid'
   else
-    lt_cv_deplibs_check_method='file_magic file format (pei*-i386(.*architecture: i386)?|pe-arm-wince|pe-x86-64)'
+    lt_cv_deplibs_check_method='file_magic file format (pei*-i386(.*architecture: i386)?|pe-arm-wince|pe-x86-64|pe-aarch64)'
     lt_cv_file_magic_cmd='$OBJDUMP -f'
   fi
   lt_cv_deplibs_check_method=pass_all