Add syscall arguments to clone hooks

[alberto-miranda]

This PR adds the missing arguments to the clone() system call, so that their values can be inspected when interception hooks are called. In our case, this is useful to keep track of what arguments have been passed to the clone() system call and react accordingly.

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This change is 

[krzycz]

Reviewed 3 of 3 files at r1.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @alberto-miranda)

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test/test_clone_thread_preload.c, line 99 at r1 (raw file):

 */
static void
hook_child(unsigned long clone_flags,

What about parent hook? Would be nice to have it tested as well.

[codecov-io]

Codecov Report

Merging #102 (f4a14f6) into master (7031a8f) will increase coverage by 0.00%.
The diff coverage is 66.66%.

@@           Coverage Diff           @@
##           master     #102   +/-   ##
=======================================
  Coverage   91.95%   91.96%           
=======================================
  Files          11       11           
  Lines         957      958    +1     
=======================================
+ Hits          880      881    +1     
  Misses         77       77           

Flag	Coverage Δ
pmemfile_tests	86.37% <33.33%> (+0.01%)	⬆️
regular_tests	90.81% <66.66%> (+<0.01%)	⬆️

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Impacted Files	Coverage Δ
include/libsyscall_intercept_hook_point.h	50.00% <ø> (ø)
src/intercept.c	80.89% <66.66%> (+0.12%)	⬆️

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