Log debuggerd connection failures

Write a message to the log file if the signal handler is not able
to connect to debuggerd.  This is especially handy if the failure
was caused by running out of file descriptors, since there's some
chance that the lack of fds relates to the crash.

Sample:

 F libc    : Fatal signal 11 (SIGSEGV) at 0xdeadbaad (code=1)
 F libc    : Unable to open connection to debuggerd: Too many open files

Bug 5926330

Change-Id: I0ff210d82ab1db39b08f328bae5e08f67a69e5d7
1 file changed