How to find headers in /usr/include/psql?

[peti]

The postgresql-devel package on openSUSE Linux install the header files for libpq into the directory /usr/include/pgsql, where the RPostgreSQL build process won't find them. Is there a way to configure that build to discover that directory during its configure phase?

Also, I kinda wonder why configure won't just call

$ pkg-config --cflags libpq
-I/usr/include/pgsql

to discover the necessary compiler flags?

[tomoakin]

Should pg_config in the PATH, the configure would call pg_config and set as such (not pkg-config).

[tomoakin]

postgresql-server-devel might contain the program pg_config in openSUSE.