Disable libunwind on aarch64

Fixes hangs when using libtcmalloc.so

Upstream-Status: Pending
Signed-off-by: Khem Raj <raj.khem@gmail.com>

Index: git/configure.ac
===================================================================
--- git.orig/configure.ac
+++ git/configure.ac
@@ -69,6 +69,11 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM(, [re
                   [default_enable_libunwind=yes
                    default_tcmalloc_pagesize=8])
 
+# Disable libunwind linking on aarch64 by default.
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM(, [return __aarch64__])],
+                  [default_enable_libunwind=no],
+                  [default_enable_libunwind=yes])
+
 AC_ARG_ENABLE([cpu-profiler],
               [AS_HELP_STRING([--disable-cpu-profiler],
                               [do not build the cpu profiler])],
