disable -fasynchronous-unwind-tables as it breaks build on armv7
Index: configure.ac
--- configure.ac.orig
+++ configure.ac
@@ -1467,13 +1467,6 @@ fi
 CFLAGS="$saved_CFLAGS"
 AC_SUBST(F_OMIT_FRAME_POINTER)
 
-dnl ------------------------------------------------------
-dnl If we are adding -fomit-frame-pointer (or if the compiler's doing it
-dnl for us, as GCC 4.6 and later do at many optimization levels), then
-dnl we should try to add -fasynchronous-unwind-tables so that our backtrace
-dnl code will work.
-TOR_CHECK_CFLAGS(-fasynchronous-unwind-tables)
-
 dnl ============================================================
 dnl Check for libseccomp