Back out "[folly][PR] [CMake] Generalize include path for dwarf.h"

Summary:
Original commit changeset: 6b5faf000e5f

Breaks builds on Ubuntu Bionic, effectivly undoing the work of D3878961.
Note: both autotools and CMake builds incorrect on Bionic, its just that
autotools build fails explicitly where CMake fails silently; failing to
detect a correctly installed libdwarf headers. The difference being that
CMake does not build symbolizer.

Reviewed By: yfeldblum

Differential Revision: D9194639

fbshipit-source-id: c6798a0672195a70ced4898535f2f932018224d5

CMake/FindLibDwarf.cmake

-find_path(LIBDWARF_INCLUDE_DIR NAMES dwarf.h)
+find_path(LIBDWARF_INCLUDE_DIR NAMES libdwarf/dwarf.h)
 mark_as_advanced(LIBDWARF_INCLUDE_DIR)
 
 find_library(LIBDWARF_LIBRARY NAMES dwarf)

CMake/folly-deps.cmake

@@ -128,7 +128,7 @@ endif()
 find_package(LibDwarf)
 list(APPEND FOLLY_LINK_LIBRARIES ${LIBDWARF_LIBRARIES})
 list(APPEND FOLLY_INCLUDE_DIRECTORIES ${LIBDWARF_INCLUDE_DIRS})
-CHECK_INCLUDE_FILE_CXX(dwarf.h FOLLY_HAVE_LIBDWARF_DWARF_H)
+CHECK_INCLUDE_FILE_CXX(libdwarf/dwarf.h FOLLY_HAVE_LIBDWARF_DWARF_H)
 
 find_package(Libiberty)
 list(APPEND FOLLY_LINK_LIBRARIES ${LIBIBERTY_LIBRARIES})

folly/experimental/symbolizer/Dwarf.cpp

@@ -18,7 +18,11 @@
 
 #include <type_traits>
 
-#include <dwarf.h>
+#if FOLLY_HAVE_LIBDWARF_DWARF_H
+#include <libdwarf/dwarf.h>
+#else
+#include <dwarf.h> // @manual
+#endif
 
 namespace folly {
 namespace symbolizer {