Disable tests on backtraces w/ unknown line numbers

mrbgems/mruby-kernel-ext/test/kernel.rb

@@ -20,6 +20,9 @@ assert('Kernel.caller, Kernel#caller') do
       bar(*args)
     end
   end
+
+  skip "backtrace isn't available" if(c.new.baz(0)[0].include?("unknown"))
+
   assert_equal "kernel.rb:#{caller_lineno}:in foo", c.new.baz(0)[0][-19..-1]
   assert_equal "bar", c.new.baz[0][-3..-1]
   assert_equal "foo", c.new.baz(0)[0][-3..-1]

mrbgems/mruby-proc-ext/test/proc.rb

@@ -7,6 +7,9 @@ def enable_debug_info?
     raise
   rescue => e
     @enable_debug_info = !e.backtrace.empty?
+    if(@enable_debug_info && e.backtrace[0].include?("(unknown)"))
+       @enable_debug_info = false
+    end
   end
 end
 

test/t/exception.rb

@@ -382,7 +382,8 @@ def backtrace_available?
   begin
     raise "XXX"
   rescue => exception
-    not exception.backtrace.empty?
+    return false if exception.backtrace.empty?
+    not exception.backtrace[0].include?("unknown")
   end
 end