SIMD1 test requires an architecture with MMX

[kroening]

The SIMD1 test uses an include that uses MMX intrinsics, which are only
available on Intel x86 architectures. This commit adds preprocessor checks
to prevent the test to fail on other architectures.

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

Merging #7050 (438aad3) into develop (a1ecd93) will increase coverage by 0.00%.
The diff coverage is 78.07%.

@@           Coverage Diff            @@
##           develop    #7050   +/-   ##
========================================
  Coverage    77.88%   77.88%           
========================================
  Files         1569     1569           
  Lines       180894   180989   +95     
========================================
+ Hits        140882   140962   +80     
- Misses       40012    40027   +15     

Impacted Files	Coverage Δ
src/solvers/smt2_incremental/object_tracking.h	100.00% <ø> (ø)
src/util/dstring.h	100.00% <ø> (ø)
src/util/std_expr.h	92.09% <0.00%> (-0.91%)	⬇️
src/solvers/prop/prop_conv_solver.cpp	87.50% <16.66%> (-1.65%)	⬇️
src/solvers/smt2/smt2_conv.cpp	68.76% <16.66%> (-0.11%)	⬇️
src/solvers/flattening/boolbv.cpp	87.08% <25.00%> (-0.76%)	⬇️
...c/solvers/smt2_incremental/convert_expr_to_smt.cpp	88.56% <92.85%> (+0.26%)	⬆️
src/goto-instrument/horn_encoding.cpp	73.24% <100.00%> (+0.53%)	⬆️
src/solvers/smt2_incremental/object_tracking.cpp	98.41% <100.00%> (+0.41%)	⬆️
...t/solvers/smt2_incremental/convert_expr_to_smt.cpp	99.68% <100.00%> (+<0.01%)	⬆️
... and 9 more

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