[libc++abi] Do not export some implementation-detail functions

Those functions started being mistakenly exported from the libc++abi
shared library after commit r344152 in 2018. Removing these symbols is
technically an ABI break. However, they are not part of the C++ ABI,
they haven't ever been re-exported from libc++, and they are not
declared in any public header, so it's very unlikely that calls to
these functions exist out there. Also, the functions have reserved
names, so any impacted user would have to have tried really hard
being broken by this removal.

Note that avoiding this kind of problem is exactly why we're now
controlling exported symbols explicitly with a textual list.

Also note that applying the hidden visibility attribute is necessary
because the list of exported symbols is only used on Apple platforms
for the time being.

Reviewers: phosek, mclow.lists, EricWF

Subscribers: christof, jkorous, dexonsmith, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D68357

git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@373602 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/itanium-base.exp b/lib/itanium-base.exp
index ff0f812..c08c711 100644
--- a/lib/itanium-base.exp
+++ b/lib/itanium-base.exp
@@ -366,8 +366,3 @@
-# Misc
diff --git a/src/cxa_exception.h b/src/cxa_exception.h
index d7999e0..c94621d 100644
--- a/src/cxa_exception.h
+++ b/src/cxa_exception.h
@@ -23,9 +23,9 @@
 static const uint64_t kOurDependentExceptionClass = 0x434C4E47432B2B01; // CLNGC++\1
 static const uint64_t get_vendor_and_language     = 0xFFFFFFFFFFFFFF00; // mask for CLNGC++
-uint64_t __getExceptionClass  (const _Unwind_Exception*);
-void     __setExceptionClass  (      _Unwind_Exception*, uint64_t);
-bool     __isOurExceptionClass(const _Unwind_Exception*);
+_LIBCXXABI_HIDDEN uint64_t __getExceptionClass  (const _Unwind_Exception*);
+_LIBCXXABI_HIDDEN void     __setExceptionClass  (      _Unwind_Exception*, uint64_t);
+_LIBCXXABI_HIDDEN bool     __isOurExceptionClass(const _Unwind_Exception*);
 struct _LIBCXXABI_HIDDEN __cxa_exception {
 #if defined(__LP64__) || defined(_LIBCXXABI_ARM_EHABI)