JavaScript Backend: Fix permission errors in testsuite

Description

Several tests throw permissions errors when run with the JS Backend. For example:

js-unknown-ghcjs-hsc2hs: ./T15758.a_hsc_make: createProcess: posix_spawnp: permission denied (Permission denied)
make: *** [Makefile:62: T15758] Error 1
*** unexpected failure for T15758(normal)
...
js-unknown-ghcjs-hsc2hs: ./hsc2hs001_hsc_make: createProcess: posix_spawnp: permission denied (Permission denied)
make: *** [Makefile:9: hsc2hs001] Error 1
*** unexpected failure for hsc2hs001(normal)
Wrong exit code for hsc2hs002()(expected 0 , actual 2 )
Stderr ( hsc2hs002 ):
js-unknown-ghcjs-hsc2hs: ./hsc2hs002_hsc_make: createProcess: posix_spawnp: permission denied (Permission denied)
make: *** [Makefile:14: hsc2hs002] Error 1
*** unexpected failure for hsc2hs002(normal)

Impacted Tests

• hsc2hs001 passes
• hsc2hs002 passes
• T15758 passes
• exec_signals passes
• T11004 passes
• T12504 passes
• T3837 passes
• hsc2hs003 passes
• typecheck.testeq1 passes