Fix memory issue in test_execprocess that shows up with valgrind

[jesper-friis]

However, this issue does not shows up when running te test program manually eo via gdb, making rather hard to debug...

Output from valgrind:

$ valgrind src/utils/tests/test_execprocess 
==714222== Memcheck, a memory error detector
==714222== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
==714222== Using Valgrind-3.19.0 and LibVEX; rerun with -h for copyright info
==714222== Command: src/utils/tests/test_execprocess
==714222== 
==714226== Syscall param execve(argv) points to unaddressable byte(s)
==714226==    at 0x48A599B: execve (syscall-template.S:120)
==714226==    by 0x401C27: exec_process (execprocess.c:116)
==714226==    by 0x401479: test_exec_process (test_execprocess.c:23)
==714226==    by 0x40189F: test_suite (test_execprocess.c:61)
==714226==    by 0x401AE9: main (test_execprocess.c:69)
==714226==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
==714226== 
** Fatal 1: cannot execute pathname /home/jesperf/prosjekter/software/dlite/build/src/utils/tests/test_uuid: Bad address
==714226== 
==714226== HEAP SUMMARY:
==714226==     in use at exit: 0 bytes in 0 blocks
==714226==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==714226== 
==714226== All heap blocks were freed -- no leaks are possible
==714226== 
==714226== For lists of detected and suppressed errors, rerun with: -s
==714226== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
F
test_exec_process failed:
        /home/jesperf/prosjekter/software/dlite/src/utils/tests/test_execprocess.c:24: 0 expected but was 256
....

3 tests, 5 assertions, 1 failures

Finished in 0.00000000 seconds (real) 0.02006200 seconds (proc)

==714222== 
==714222== HEAP SUMMARY:
==714222==     in use at exit: 0 bytes in 0 blocks
==714222==   total heap usage: 228 allocs, 228 frees, 15,096 bytes allocated
==714222== 
==714222== All heap blocks were freed -- no leaks are possible
==714222== 
==714222== For lists of detected and suppressed errors, rerun with: -s
==714222== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

Output without valgrind:

$ src/utils/tests/test_execprocess 
bswap_16           : OK
bswap_32           : OK
bswap_64           : OK
md5                : OK
sha1               : OK
uuid3              : OK
uuid5              : OK
uuid_as_string     : OK
uuid_from_string   : OK
.....

3 tests, 5 assertions, 0 failures

Finished in 0.00000000 seconds (real) 0.00000000 seconds (proc)

[jesper-friis]

Fixed