[test][ORC-RT] Disable elfnix_platform tests on non-x86_64 platforms

ORC ELFNixPlatform currently only supports x86_64.

diff --git a/compiler-rt/test/orc/TestCases/Linux/ehframe-default.cpp b/compiler-rt/test/orc/TestCases/FreeBSD/x86-64/ehframe-default.cpp
similarity index 100%
rename from compiler-rt/test/orc/TestCases/Linux/ehframe-default.cpp
rename to compiler-rt/test/orc/TestCases/FreeBSD/x86-64/ehframe-default.cpp

diff --git a/compiler-rt/test/orc/TestCases/Linux/ehframe-libunwind.cpp b/compiler-rt/test/orc/TestCases/FreeBSD/x86-64/ehframe-libunwind.cpp
similarity index 100%
rename from compiler-rt/test/orc/TestCases/Linux/ehframe-libunwind.cpp
rename to compiler-rt/test/orc/TestCases/FreeBSD/x86-64/ehframe-libunwind.cpp

diff --git a/compiler-rt/test/orc/TestCases/FreeBSD/ehframe-default.cpp b/compiler-rt/test/orc/TestCases/Linux/x86-64/ehframe-default.cpp
similarity index 100%
rename from compiler-rt/test/orc/TestCases/FreeBSD/ehframe-default.cpp
rename to compiler-rt/test/orc/TestCases/Linux/x86-64/ehframe-default.cpp

diff --git a/compiler-rt/test/orc/TestCases/FreeBSD/ehframe-libunwind.cpp b/compiler-rt/test/orc/TestCases/Linux/x86-64/ehframe-libunwind.cpp
similarity index 100%
rename from compiler-rt/test/orc/TestCases/FreeBSD/ehframe-libunwind.cpp
rename to compiler-rt/test/orc/TestCases/Linux/x86-64/ehframe-libunwind.cpp