I've just upgraded to MacOS Mavericks (10.9) and I'm using the Postgres.app install.
I followed the instructions in the answer to Enabling PostgreSQL support in PHP on Mac OS X to make PGSQL accessible again. I included the --with-pgsql=/path/to/pgsql option to address the "Cannot find libpq-fe.h" error and pgsql access is successfully enabled.
However, when I came to configuring pdo_pgsql I got the "Cannot find libpq-fe.h" error despite specifying the install path exactly as I did in the pgsql configuration above.
Here's a snip from the successful pgsql config - note the double slash in the pg_config check response.
pgsql$ ./configure --with-pgsql=/Applications/Postgres.app/Contents/MacOS/bin/
<...>
checking for pg_config... /Applications/Postgres.app/Contents/MacOS/bin//pg_config
<...>
'pg_config' is where it should be:
$ ls /Applications/Postgres.app/Contents/MacOS/bin/pg_conf*
/Applications/Postgres.app/Contents/MacOS/bin/pg_config
But, when configuring pdo_pgsql, pg_config is not found at all.
pdo_pgsql$ ./configure --with-pgsql=/Applications/Postgres.app/Contents/MacOS/bin/
<...>
checking for pg_config... not found
configure: error: Cannot find libpq-fe.h. Please specify correct PostgreSQL installation path
I have tried specifying the path with and without trailing slash, and with or without the bin directory, all of which work with pgsql and none of which work with pdo_pgsql.