BUG #3867: PQconnectdb(NULL) cores instead of errors.

The following bug has been logged online:

Bug reference:      3867
Logged by:          Ken Lorber
Email address:      keni@stacksafe.com
PostgreSQL version: 8.3beta4
Operating system:   Mac OSX
Description:        PQconnectdb(NULL) cores instead of errors.
Details:

PQconnectdb(NULL) cores in strdup() in interfaces/libpq/fe-connect.c:3091
(conninfo_parse).  Throwing an error would be more useful.

To reproduce:
1) configure, make, make install
2) set conninfo = NULL at line 38 of src/test/examples/testlibpq.c
3) make testlibpq
4) ./testlibpq
result should be a core or bus error or similar fatal error

gdb shows:
0x90013413 in strdup ()
(gdb) where
#0  0x90013413 in strdup ()
#1  0x0001cc37 in conninfo_parse ()
#2  0x0001d679 in connectOptions1 ()
#3  0x0001d9a1 in PQconnectStart ()
#4  0x0001d9e4 in PQconnectdb ()
#5  0x00001c2e in main ()

Thanks!