Remove generated generator function name from test

Get the generated function names out of the test output.

hphp/test/quick/debugger/flow2.php.expectf

@@ -114,7 +114,7 @@ hphpd> break flow2.php:12
 Breakpoint 2 set on line 12 of flow2.php
 hphpd> @test(2)
 Constructor
-Breakpoint 1 reached at 31231001122_1() on line 10 of %s/flow2.php
+Breakpoint 1 reached at %s() on line 10 of %s/flow2.php
    9 function genFoo($a) {
   10   $a = bar($a);
   11   $z = yield $a+5;
@@ -126,7 +126,7 @@ Break at foo() on line 40 of %s/flow2.php
   41     var_dump($x);
 
 hphpd> continue
-Breakpoint 2 reached at 31231001122_1() on line 12 of %s/flow2.php
+Breakpoint 2 reached at %s() on line 12 of %s/flow2.php
   11   $z = yield $a+5;
   12   yield $z+1;
   13   error_log('Finished in genFoo');