Avoid usage of jl_error() in check_cmdline()

This is the same as #45765 where
we use `jl_error()` too early to get backtraces, but too late to fail
the supposed guard `if` statement that should prevent us from trying to
take a backtrace.  X-ref: #45847

Author: staticfloat

src/processor.cpp

@@ -822,20 +822,24 @@ static inline void check_cmdline(T &&cmdline, bool imaging)
     // sysimg means. Make it an error for now.
     if (!imaging) {
         if (cmdline.size() > 1) {
-            jl_error("More than one command line CPU targets specified "
-                     "without a `--output-` flag specified");
+            jl_safe_printf("More than one command line CPU targets specified "
+                      "without a `--output-` flag specified");
+            exit(1);
         }
         if (cmdline[0].en.flags & JL_TARGET_CLONE_ALL) {
-            jl_error("\"clone_all\" feature specified "
-                     "without a `--output-` flag specified");
+            jl_safe_printf("\"clone_all\" feature specified "
+                      "without a `--output-` flag specified");
+            exit(1);
         }
         if (cmdline[0].en.flags & JL_TARGET_OPTSIZE) {
-            jl_error("\"opt_size\" feature specified "
-                     "without a `--output-` flag specified");
+            jl_safe_printf("\"opt_size\" feature specified "
+                      "without a `--output-` flag specified");
+            exit(1);
         }
         if (cmdline[0].en.flags & JL_TARGET_MINSIZE) {
-            jl_error("\"min_size\" feature specified "
-                     "without a `--output-` flag specified");
+            jl_safe_printf("\"min_size\" feature specified "
+                      "without a `--output-` flag specified");
+            exit(1);
         }
     }
 }