Our Libunwind does not require Liblzma.

Index: cmake/FindLibunwind.cmake
--- cmake/FindLibunwind.cmake.orig
+++ cmake/FindLibunwind.cmake
@@ -23,17 +23,6 @@ if(NOT LIBUNWIND_LIBRARIES STREQUAL "LIBUNWIND_LIBRARI
   endif()
 endif()
 
-# some versions of libunwind need liblzma, and we don't use pkg-config
-# so we just look whether liblzma is installed, and add it if it is.
-# It might not be actually needed, but doesn't hurt if it is not.
-# We don't need any headers, just the lib, as it's privately needed.
-message(STATUS "looking for liblzma")
-find_library(LIBLZMA_LIBRARIES lzma )
-if(NOT LIBLZMA_LIBRARIES STREQUAL "LIBLZMA_LIBRARIES-NOTFOUND")
-  message(STATUS "liblzma found")
-  set(LIBUNWIND_LIBRARIES "${LIBUNWIND_LIBRARIES};${LIBLZMA_LIBRARIES}")
-endif()
-
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(Libunwind "Could not find libunwind" LIBUNWIND_INCLUDE_DIR LIBUNWIND_LIBRARIES)
 # show the LIBUNWIND_INCLUDE_DIR and LIBUNWIND_LIBRARIES variables only in the advanced view
