x86_64 tests assume they're being run on an x86_64 host

[jonathonpenix]

Description

There's a number of x86_64 test failures when building/testing eld on AArch64 Linux.

See the log here for full output, but the relevant test failures are:

eld :: x86_64/linux/DefaultImageBase/DefaultImageBase.test
eld :: x86_64/linux/DynamicDataCall/DynamicDataCall.test
eld :: x86_64/linux/DynamicRelocsForAbs64/DynamicRelocsforAbs64.test
eld :: x86_64/linux/EmulationSupport/EmulationOption.test
eld :: x86_64/linux/TlsGDnonpreemptible/TlsGDnonpreemptible.test
eld :: x86_64/linux/TlsGDpreemptible/TlsGDpreemptible.test
eld :: x86_64/linux/TlsIEModel/TlsIEModel.test
eld :: x86_64/linux/TlsLDModel/TlsLDModel.test
eld :: x86_64/linux/relocCOPY/relocCOPY.test
eld :: x86_64/linux/relocGOTPCREL/relocGOTPCREL.test
eld :: x86_64/linux/relocIRELATIVE/relocIRELATIVE.test
eld :: x86_64/linux/relocPLT32Static/relocPLT32Static.test
eld :: x86_64/linux/relocPLT32dynamic/relocPLT32dynamic.test

Failures either look like "cannot execute binary file: Exec format error" or "Fatal: cannot read file 'crt1.o'"

The exec format errors are just a mismatch between x86 and aarch64--presumably these tests should be gated depending on the host architecture (or, presence of an appropriate qemu, etc.)

The "Fatal: cannot read file 'crt1.o'" I think is just that clang can't find the runtime libs it is by default looking for, for the relevant target. That part I think is a toolchain issue (the default invocation doesn't work/the toolchain isn't really "self contained" for the targets it supports). But, the tests with these errors that I spot checked also seem to execute the resulting binaries, so I'm guessing we again just want to gate these based on the host arch being x86.

[quic-seaswara]

@quic-shaksuma we were planning to run the tests using qemu when its available, can you update where we are on that ?

If qemu is not available we will need to disable the tests.