change in location of unixodbc causing build failure

[Tim Dickson <dickson.tim@xxxxxxxxxxxxxx>]

hi all, my distro's unixodb package has changed very slightly in that 
header files are no longer directly in /usr/include/
they are now in /usr/include/unixodbc/

the pkg-config file was suitably updated in the package, so
pkg-config --cflags odbc
reports
 -I/usr/include/unixodbc
which looks correct.

unfortunately trying to create the gambas package fails at

Making all in gb.db.odbc
Making all in src
  CC       gb_db_odbc_la-main.lo
In file included from /usr/include/sql.h:19,
                 from main.c:45:
/usr/include/sqltypes.h:56:10: fatal error: unixodbc.h: No such file or 
directory
   56 | #include "unixodbc.h"
      |          ^~~~~~~~~~~~
compilation terminated.

so it appears as if the gb.db.odbc module is not picking up the new 
location even though I do a
./reconf-all
before running configure and make and make install

my system has the following odbc related stuff showing in pkg-config , 
by running   pkg-config --list-all|grep odbc
odbcinst      idbcinst (unixODBC) - unixODBC Configuration Library
libiodbc       iODBC - iODBC Driver Manager
odbccr         odbccr (unixODBC) - unixODBC Cursor Library
odbc            odbc (unixODBC) - unixODBC Driver Manager library

any ideas?
(for reference the build script is the same as 
https://slackbuilds.org/slackbuilds/15.0/development/gambas3/gambas3.SlackBuild
but with version bumped to 3.19.3  )
regards, Tim