Cut build config items for bits/functexcept.h

Summary:
[Folly] Cut build config items for `bits/functexcept.h`.

Folly no longer uses the non-portable functions declared in that internal libstdc++ header.

Reviewed By: mzlee

Differential Revision: D7119064

fbshipit-source-id: 6879dc6a5bc490726b188d65d7686a2eca136980

CMake/FollyConfigChecks.cmake

@@ -7,7 +7,6 @@ include(CheckTypeSize)
 include(CheckCXXCompilerFlag)
 
 CHECK_INCLUDE_FILE_CXX(malloc.h FOLLY_HAVE_MALLOC_H)
-CHECK_INCLUDE_FILE_CXX(bits/functexcept.h FOLLY_HAVE_BITS_FUNCTEXCEPT_H)
 CHECK_INCLUDE_FILE_CXX(bits/c++config.h FOLLY_HAVE_BITS_CXXCONFIG_H)
 CHECK_INCLUDE_FILE_CXX(features.h FOLLY_HAVE_FEATURES_H)
 CHECK_INCLUDE_FILE_CXX(linux/membarrier.h FOLLY_HAVE_LINUX_MEMBARRIER_H)

CMake/folly-config.h.cmake

@@ -36,7 +36,6 @@
 #cmakedefine FOLLY_HAVE_LIBGLOG 1
 
 #cmakedefine FOLLY_HAVE_MALLOC_H 1
-#cmakedefine FOLLY_HAVE_BITS_FUNCTEXCEPT_H 1
 #cmakedefine FOLLY_HAVE_BITS_CXXCONFIG_H 1
 #cmakedefine FOLLY_HAVE_FEATURES_H 1
 #cmakedefine FOLLY_HAVE_LINUX_MEMBARRIER_H 1