MDL-70627 filters: aarch64 mimetex type support for filter tex notation

Amended to correct permissions.

filter/tex/lib.php

@@ -51,9 +51,14 @@ function filter_tex_get_executable($debug=false) {
     }
 
     switch (PHP_OS) {
-        case "Linux":   return "$CFG->dirroot/filter/tex/mimetex.linux";
         case "Darwin":  return "$CFG->dirroot/filter/tex/mimetex.darwin";
         case "FreeBSD": return "$CFG->dirroot/filter/tex/mimetex.freebsd";
+        case "Linux":
+            if (php_uname('m') == 'aarch64') {
+                return "$CFG->dirroot/filter/tex/mimetex.linux.aarch64";
+            }
+
+            return "$CFG->dirroot/filter/tex/mimetex.linux";
     }
 
     print_error('mimetexisnotexist', 'error');

filter/tex/readme_moodle.txt

@@ -16,6 +16,12 @@ Linux
 2/ go into directory with extracted source files
 3/ execute "cc -DAA mimetex.c gifsave.c -lm -o mimetex.linux"
 
+Linux aarch64
+=====
+1/ install gcc
+2/ go into directory with extracted source files
+3/ execute "cc -DAA mimetex.c gifsave.c -lm -o mimetex.linux.aarch64"
+
 FreeBSD
 =======
 1/ go into directory with extracted source files