Annotate exit/trap with noreturn & inaccessiblememonly

[vchuravy]

This should help Enzyme to not assume that this assembly has
any effects it needs to handle.

[codecov]

Codecov Report

Base: 86.71% // Head: 86.78% // Increases project coverage by +0.06% 🎉

Coverage data is based on head (5121bd0) compared to base (a61466c).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #359      +/-   ##
==========================================
+ Coverage   86.71%   86.78%   +0.06%     
==========================================
  Files          24       24              
  Lines        2801     2808       +7     
==========================================
+ Hits         2429     2437       +8     
+ Misses        372      371       -1     

Impacted Files	Coverage Δ
src/irgen.jl	95.28% <100.00%> (+0.02%)	⬆️
src/ptx.jl	92.79% <100.00%> (+0.03%)	⬆️
src/utils.jl	94.44% <100.00%> (+0.69%)	⬆️
src/debug.jl	94.44% <0.00%> (+2.77%)	⬆️

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[maleadt]

LGTM

[jpsamaroo]

These attributes are probably incompatible with AMDGPU's exception handling infrastructure, which does a variety of things like accessing a shared hostcall buffer, accessing locks in local (shared) memory, and soon many more things as make enhancements. We should probably add an interface function to check if the target's exception handling functions can be given these attributes.