[m-rev.] diff: add some initial support for Linux on aarch64

[Julien Fischer]

Add some initial support for Linux on aarch64.

configure.ac:
     Do not run the test for GCC labels on aarch64; it goes
     into a loop on aarch64.

     Enable shared libraries for the aarch64*linux* configuration.

Julien.

diff --git a/configure.ac b/configure.ac
index e88692ce1..c7afb1255 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2419,6 +2419,12 @@ case "$ac_cv_prog_gcc" in yes)
              mercury_cv_asm_labels=no
              mercury_cv_gcc_labels=no
              ;;
+        aarch64*)
+        # The test for GCC labels goes into a loop on AArch64.
+            MERCURY_MSG("gcc labels do not work on AArch64")
+            mercury_cv_asm_labels=no
+            mercury_cv_gcc_labels=no
+            ;;
      esac
      ;;
  esac
@@ -4178,6 +4184,10 @@ if test "$mercury_cv_enable_shared_libs" = "yes"; then
              AC_MSG_RESULT(yes)
              EXT_FOR_SHARED_LIB=so
              ;;
+        aarch64*-linux|aarch64*-linux-gnu)
+            AC_MSG_RESULT(yes)
+            EXT_FOR_SHARED_LIB=so
+            ;;
          *-freebsd*)
              # Tested on FreeBSD 10.1 i386/amd64.
              AC_MSG_RESULT(yes)