Initial support for 64 bit ARM

This adds support for 64 bit ARM cores as used in many high-end phones
such as all iPhones beginning with the 5s. While these newer phones
still run 32 bit ARM code, Apple doesn't allow apps to be submitted to
the app store if they don't provide a 64 bit build.

This commit adds a new arm64 arch and renames arm to arm32 to stay
consistent with the other architectures. The name arm can still be used
for configuring because it has been added as an alias for arm32.

Additionally, the one piece of ARM inline assembly that can be found in
Botan doesn't work on 64 bit ARM, so I use the solution that has been
proposed in #180: Use __builtin_bswap32 instead of inline assembly.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/build-data/arch/arm64.txt b/src/build-data/arch/arm64.txt
new file mode 100644
index 000000000..362cf88d3
--- /dev/null
+++ b/src/build-data/arch/arm64.txt
@@ -0,0 +1,12 @@
+endian little
+wordsize 64
+
+family arm
+
+<aliases>
+aarch64
+</aliases>
+
+<submodels>
+armv8-a
+</submodels>