Adapt GAP_ExecuteProcess signature

[lgoettgens]

to pass tests in testinstall/kernel/streams.tst.

Resolves #1012 in the case that use_orig_ExecuteProcess = true, i.e. until #908 is worked on.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.75%. Comparing base (be6e4e2) to head (49945b0).

Files with missing lines	Patch %	Lines
src/exec.jl	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1131      +/-   ##
==========================================
+ Coverage   74.66%   81.75%   +7.09%     
==========================================
  Files          55       50       -5     
  Lines        4713     3821     -892     
==========================================
- Hits         3519     3124     -395     
+ Misses       1194      697     -497     

Files with missing lines	Coverage Δ
src/exec.jl	15.00% <50.00%> (ø)

... and 7 files with indirect coverage changes