[libunwind] Move errno.h and signal.h includes under the block where they're needed (#78054)

Commit fc1c478709e3 added includes of <signal.h> and <errno.h> to
UnwindCursor.hpp. The library previously built on platforms where these
headers are not provided. These headers should be included only in the
case where they are actually needed, i.e. on Linux.

GitOrigin-RevId: c1a442462d9d47f86392da7e7019ab218d7a3088
1 file changed
tree: 58c14a6a577ec7d64a83bb38a4b366b145e7dfc7
  1. cmake/
  2. docs/
  3. include/
  4. src/
  5. test/
  6. .clang-format
  7. CMakeLists.txt
  8. LICENSE.TXT