BUG #15424: usr/bin/ld: skipping incompatible /opt/PostgreSQL/9.6/lib/libecpg.so when searching for -lecpg

The following bug has been logged on the website:

Bug reference: 15424
Logged by: ramakrishnan r
Email address: prakash(dot)ramakrishnan(dot)ap(at)nielsen(dot)com
PostgreSQL version: 9.6.3
Operating system: RHAT 7.3
Description:

Hi Postgres Team,

We are facing incompatible issues with ECPG and PQ library files while
compiling the code. Currently, we are building the 32-bit application on the
64-bit Linux machine.

Error:

/usr/bin/ld: skipping incompatible /opt/PostgreSQL/9.6/lib/libecpg.so when
searching for -lecpg
/usr/bin/ld: skipping incompatible /opt/PostgreSQL/9.6/lib/libecpg.a when
searching for -lecpg
/usr/bin/ld: cannot find -lecpg
/usr/bin/ld: skipping incompatible /opt/PostgreSQL/9.6/lib/libpq.so when
searching for -lpq
/usr/bin/ld: skipping incompatible /opt/PostgreSQL/9.6/lib/libpq.a when
searching for -lpq
/usr/bin/ld: cannot find -lpq

Linux Configuration:

Linux lhrrheteld002 3.10.0-693.11.1.el7.x86_64 #1 SMP Fri Oct 27 05:39:05
EDT 2017 x86_64 x86_64 x86_64 GNU/Linux

Postgres version on lhrrheteld002:

psql.bin (9.6.3)