Enable more CLIF tests on AArch64

The tests for the SIMD floating-point maximum and minimum operations
require particular care because the handling of the NaN values is
non-deterministic and may vary between platforms. There is no way to
match several NaN values in a test, so the solution is to extract the
non-deterministic test cases into a separate file that is subsequently
replicated for every backend under test, with adjustments made to the
expected results.

Copyright (c) 2021, Arm Limited.

cranelift/filetests/filetests/regress/allow-relaxation-shrink.clif

@@ -1,4 +1,5 @@
 test compile
+target aarch64
 target x86_64 legacy
 
 ; This checks that code shrink is allowed while relaxing code, when code shrink