[libc++] Take 2: Replace uses of _LIBCPP_ALWAYS_INLINE by _LIBCPP_INLINE_VISIBILITY

Summary:
We never actually mean to always inline a function -- all the uses of
the macro I could find are actually attempts to control the visibility
of symbols. This is better described by _LIBCPP_INLINE_VISIBILITY, which
is actually always defined the same.

This change is orthogonal to the decision of what we're actually going
to do with _LIBCPP_INLINE_VISIBILITY -- it just simplifies things by
having one canonical way of doing things.

Note that this commit had originally been applied in r336369 and then
reverted in r336382 because of unforeseen problems. Both of these problems
have now been fixed.

Reviewers: EricWF, mclow.lists

Subscribers: christof, dexonsmith, erikvanderpoel

Differential Revision: https://reviews.llvm.org/D48892

llvm-svn: 336866
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: dc7200b486b6c5b5229abcee97c160145cc3d955
diff --git a/include/cmath b/include/cmath
index 917928a..ffb1c46 100644
--- a/include/cmath
+++ b/include/cmath
@@ -547,7 +547,7 @@
 #endif
 
 template <class _A1>
-_LIBCPP_ALWAYS_INLINE
+_LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR typename enable_if<is_floating_point<_A1>::value, bool>::type
 __libcpp_isnan_or_builtin(_A1 __lcpp_x) _NOEXCEPT
 {
@@ -559,7 +559,7 @@
 }
 
 template <class _A1>
-_LIBCPP_ALWAYS_INLINE
+_LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR typename enable_if<!is_floating_point<_A1>::value, bool>::type
 __libcpp_isnan_or_builtin(_A1 __lcpp_x) _NOEXCEPT
 {
@@ -567,7 +567,7 @@
 }
 
 template <class _A1>
-_LIBCPP_ALWAYS_INLINE
+_LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR typename enable_if<is_floating_point<_A1>::value, bool>::type
 __libcpp_isinf_or_builtin(_A1 __lcpp_x) _NOEXCEPT
 {
@@ -579,7 +579,7 @@
 }
 
 template <class _A1>
-_LIBCPP_ALWAYS_INLINE
+_LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR typename enable_if<!is_floating_point<_A1>::value, bool>::type
 __libcpp_isinf_or_builtin(_A1 __lcpp_x) _NOEXCEPT
 {
@@ -587,7 +587,7 @@
 }
 
 template <class _A1>
-_LIBCPP_ALWAYS_INLINE
+_LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR typename enable_if<is_floating_point<_A1>::value, bool>::type
 __libcpp_isfinite_or_builtin(_A1 __lcpp_x) _NOEXCEPT
 {
@@ -599,7 +599,7 @@
 }
 
 template <class _A1>
-_LIBCPP_ALWAYS_INLINE
+_LIBCPP_INLINE_VISIBILITY
 _LIBCPP_CONSTEXPR typename enable_if<!is_floating_point<_A1>::value, bool>::type
 __libcpp_isfinite_or_builtin(_A1 __lcpp_x) _NOEXCEPT
 {