BUG #14975: [pgrpms] make build10 for postgresql fails

The following bug has been logged on the website:

Bug reference:      14975
Logged by:          tbe
Email address:      thomas.berger@1und1.de
PostgreSQL version: 10.0
Operating system:   EL-7
Description:

Building the rpm from the pgrpms repository for postgresql-10 fails with

>Getting
https://www.postgresql.org/files/documentation/pdf/%{pgmajorversion}/postgresql-%{pgmajorversion}-A4.pdf
to ./postgresql-%{pgmajorversion}-A4.pdf
>  % Total    % Received % Xferd  Average Speed   Time    Time     Time
Current
>                                 Dload  Upload   Total   Spent    Left
Speed
>  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--
 0
>curl: (22) The requested URL returned error: 404 Not Found

The pgmajorversion is defined in Makefile.global-PG10 as parameter for the
rpmbuild command, but within the prep target in Makefile.global, spectool is
invoked without any extra parameters.