tests: change postgresql socket dir to /tmp

Dependencies

• [2] 3HVZCXJR Shut up warnings
• [3] LAJHRL6O Fix tests
• [4] 7VQ4ALFY Update "make check" for the new queue runner
• [5] UQYHPQ6U Run PostgreSQL during "make check"
• [*] GBCPEGYC Add a .gitignore
• [*] G2ZB6464 first test, not yet in buildprocess
• [*] OB7GB5DL Test environment cleanups

Change contents

• edit in .gitignore at line 35
  [2.33]
  + result
• edit in tests/Makefile.am at line 15
  [9.24]

  [3.151]
  + PGHOST=/tmp \
• replacement in tests/set-up.pl at line 3
  [4.273]→[4.273:348](∅→∅)
  − system("pg_ctl -D postgres -o \"-F -p 6433 -h ''\" -w start") == 0 or die;
  [4.273]

  [4.348]
  + system("pg_ctl -D postgres -o \"-F -p 6433 -h '' -k /tmp \" -w start") == 0 or die;