commit f16e172866e10a233d2f8029b0be52927a906f22
author Nico Weber <nicolasweber@gmx.de> Tue Jul 30 14:32:47 2019 +0000
committer Nico Weber <nicolasweber@gmx.de> Tue Jul 30 14:32:47 2019 +0000
tree 5d4a6b3f681a48399ed0dae4a82c4ba43d8a1684
parent b255afb4ac243749efea4fb3b99b67cdcebdac2f

libcxx: Define __STDCPP_THREADS__ to 1, not to __cplusplus.

[cpp.predefined]p2:

   __STDCPP_THREADS__
    Defined, and has the value integer literal 1, if and only if a program
    can have more than one thread of execution .

Also define it only if it's not defined already, since it's supposed
to be defined by the compiler.

Also move it from thread to __config (which requires setting it only
if _LIBCPP_HAS_NO_THREADS is not defined).

Part of PR33230. The intent is to eventually make the compiler define
this instead.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@367316 91177308-0d34-0410-b5e6-96231b3b80d8