Add AIX support to Path.inc, Host.h, and CMake.

Patch by Andrew Paprocki!

Differential Revision: https://reviews.llvm.org/D18359

llvm-svn: 276045
diff --git a/llvm/cmake/modules/HandleLLVMOptions.cmake b/llvm/cmake/modules/HandleLLVMOptions.cmake
index 22b4408..9dafdc3 100644
--- a/llvm/cmake/modules/HandleLLVMOptions.cmake
+++ b/llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -79,11 +79,11 @@
   if(UNIX)
     set(LLVM_ON_WIN32 0)
     set(LLVM_ON_UNIX 1)
-    if(APPLE)
+    if(APPLE OR ${CMAKE_SYSTEM_NAME} MATCHES "AIX")
       set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
-    else(APPLE)
+    else()
       set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
-    endif(APPLE)
+    endif()
   else(UNIX)
     MESSAGE(SEND_ERROR "Unable to determine platform")
   endif(UNIX)