quiet inline configure check misses a step for clang

Hi,

The current quiet inline test doesn't work for clang. As e.g. evidenced in
http://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=gull&dt=2014-04-03%2007%3A49%3A26&stg=configure
configure thinks it's not quiet.

Which means that postgres compiled with a recent clang will be noticably
slower than it needs to be.

The reason for that is that clang is smart and warns about static inline
if they are declared locally in the .c file, but not if they are
declared in a #included file. That seems to be a reasonable
behaviour...

I think that needs to be fixed. We either can make the configure test
considerably more complex or simply drop the requirement for quiet
inline.

Comments?

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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