Don't link against libm and libpthread which don't exist in BeOS/Haiku. Also,
Haiku like Linux provides <regex.h>, so use it. Patch by Paul Davey!

llvm-svn: 106620
diff --git a/llvm/utils/TableGen/CMakeLists.txt b/llvm/utils/TableGen/CMakeLists.txt
index 85847f1..972989b 100644
--- a/llvm/utils/TableGen/CMakeLists.txt
+++ b/llvm/utils/TableGen/CMakeLists.txt
@@ -41,6 +41,6 @@
 if( MINGW )
   target_link_libraries(tblgen imagehlp psapi)
 endif( MINGW )
-if( LLVM_ENABLE_THREADS AND HAVE_LIBPTHREAD )
+if( LLVM_ENABLE_THREADS AND HAVE_LIBPTHREAD AND NOT BEOS )
   target_link_libraries(tblgen pthread)
 endif()