arm64: extable: sort the exception table at build time

As is done for other architectures, sort the exception table at
build-time rather than during boot.

Since sortextable appears to be a standalone C program relying on the
host elf.h to provide EM_AARCH64, I've had to add a conditional check in
order to allow cross-compilation on machines that aren't running a
bleeding-edge libc-dev.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/scripts/sortextable.c b/scripts/sortextable.c
index 1f10e89..f9ce116 100644
--- a/scripts/sortextable.c
+++ b/scripts/sortextable.c
@@ -31,6 +31,10 @@
 #include <tools/be_byteshift.h>
 #include <tools/le_byteshift.h>
 
+#ifndef EM_AARCH64
+#define EM_AARCH64	183
+#endif
+
 static int fd_map;	/* File descriptor for file being modified. */
 static int mmap_failed; /* Boolean flag. */
 static void *ehdr_curr; /* current ElfXX_Ehdr *  for resource cleanup */
@@ -249,6 +253,7 @@
 		custom_sort = sort_relative_table;
 		break;
 	case EM_ARM:
+	case EM_AARCH64:
 	case EM_MIPS:
 		break;
 	}  /* end switch */