Backport check for Thumb instructions from configure script

The recompiler can't handle Thumb instructions, so they must be disabled.
This is accomplished via the `-marm` flag being set for different platforms.

However, when using `platform=unix` and manually configuring the build,
the check for Thumb instructions is not done in `Makefile.libretro`.
Therefore, when building with a compiler that defaults to Thumb instructions
(e.g. ODROID-XU4), the build can fail with this error:

    libpcsxcore/new_dynarec/backends/psx/pcsxmem.c:18:2: error:
     #error the dynarec is incompatible with Thumb functions,
    libpcsxcore/new_dynarec/backends/psx/pcsxmem.c:19:2: error:
     #error please add -marm to compile flags

To address this, we simply backport the define check from the configure script
for when we build with `ARCH=arm`. This change doesn't affect the buildbot.

0 files changed, 0 insertions, 0 deletions