tests/features/output-sync failure on Solaris 10

[Paul Eggert]

'make check' fails on Solaris 10 in multiple ways. I posted a fix for 
the functions/shell problem recently 
<https://lists.gnu.org/archive/html/bug-make/2019-10/msg00025.html>. 
This bug report is about a different problem, with features/output-sync, 
which fails as follows:

        $ cd tests
        $ perl  ./run_make_tests.pl -srcdir /var/run/rpc_door\
        /eggert/make-4.2.92 -make ../make  features/output-sync
        
------------------------------------------------------------------------------
               Running tests for GNU make on SunOS kiwi.cs.ucla.edu 5.10 sun4u
                                       GNU Make 4.2.92
        
------------------------------------------------------------------------------

        Clearing work...
        Making work dirs...

        features/output-sync ....................................
        Test timed out after 30 seconds
	Error running /var/run/rpc_door/eggert/make-4.2.92/tests/../make 
(expected 0; got 14): /var/run/rpc_door/eggert/make-4.2.92/tests/../make 
-f work/features/output-sync.mk -j -Orecurse

        Caught signal 14!

        Test timed out after 30 seconds
	Error running /var/run/rpc_door/eggert/make-4.2.92/tests/../make 
(expected 0; got 14): /var/run/rpc_door/eggert/make-4.2.92/tests/../make 
-f work/features/output-sync.mk.1 -j --output-sync=target

        Caught signal 14!

        Test timed out after 30 seconds
	Error running /var/run/rpc_door/eggert/make-4.2.92/tests/../make 
(expected 0; got 14): /var/run/rpc_door/eggert/make-4.2.92/tests/../make 
-f work/features/output-sync.mk.1 -j --output-sync=target x=

        Caught signal 14!
        FAILED (12/15 passed)

        3 Tests in 1 Category Failed (See .diff* files in work dir for details) 
:-(


Changing the test to timeout after 120 seconds did not help. I am 
attaching the output of running the perl command under "truss -f" so 
that you can see what system calls are being executed in what order.

make-perl-Solaris-10-truss.out.xz
Description: application/xz