Opt AIX out of the change and update release notes to match

Author: rnk

clang/docs/ReleaseNotes.rst

@@ -179,11 +179,11 @@ Non-comprehensive list of changes in this release
   Currently, the use of ``__builtin_dedup_pack`` is limited to template arguments and base
   specifiers, it also must be used within a template context.
 
-- On non-Windows platforms, Clang now builds as a large shared library,
-  ``libclang-cpp``, by default. To revert to the old behavior of producing and
-  linking static libraries, pass ``-DCLANG_LINK_CLANG_DYLIB=OFF`` to CMake when
-  configuring your build. The new behavior matches LLVM, which also builds as a
-  large shared library.
+- On all platforms excluding Windows and AIX, Clang now builds as a large shared
+  library, ``libclang-cpp``, by default. To revert to the old behavior of
+  producing and linking static libraries, pass ``-DCLANG_LINK_CLANG_DYLIB=OFF``
+  to CMake when configuring your build. The new behavior matches LLVM, which
+  also builds as a large shared library.
 
 New Compiler Flags
 ------------------

llvm/CMakeLists.txt

@@ -934,7 +934,7 @@ endif()
 
 # Link the tools against the libllvm DSO by default.
 set(LLVM_LINK_LLVM_DYLIB_default ON)
-if (BUILD_SHARED_LIBS OR WIN32)
+if (BUILD_SHARED_LIBS OR WIN32 OR CMAKE_SYSTEM_NAME MATCHES "AIX")
   set(LLVM_LINK_LLVM_DYLIB_default OFF)
 endif()
 

llvm/docs/ReleaseNotes.md

@@ -69,10 +69,10 @@ Changes to LLVM infrastructure
 Changes to building LLVM
 ------------------------
 
-* On non-Windows platforms, LLVM now builds as a large shared library, `libLLVM`,
-  by default. To revert to the old behavior of producing and linking static
-  libraries, pass ``-DLLVM_LINK_LLVM_DYLIB=OFF`` to CMake when configuring your
-  build.
+* On all platforms excluding Windows and AIX, LLVM now builds as a large shared
+  library, `libLLVM`, by default. To revert to the old behavior of producing and
+  linking static libraries, pass ``-DLLVM_LINK_LLVM_DYLIB=OFF`` to CMake when
+  configuring your build.
 
 Changes to TableGen
 -------------------