Ruby » Ruby master

symbol.c: fix memory leak from global fstr hash

• symbol.c (rb_gc_free_dsymbol): delete from global fstr hash
• test/ruby/test_symbol.rb (test_symbol_fstr_leak): test for bug
  [ruby-core:67268] [Bug #10686]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49090 b2dd03c8-39d4-4d8f-98ff-823fe69b080e