Ruby » Ruby master

Fix broken pow() on x64-mingw32

• include/ruby/win32.h (rb_w32_pow): add new function.
  We use powl() instead of broken pow() for x64-mingw32. This workaround
  fixes test failures related to floating point numeric.
  [ruby-core:46686] [Bug #6784]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36522 b2dd03c8-39d4-4d8f-98ff-823fe69b080e