It is nice that libmcsapi provides a .pc file for pkg-config, but it i s regretable that this is incorrect, at least for CentOS.
The install locations are /usr/lib64 and /usr/include respectively for lib and include files. The supplied libmcsapi.pc file though looks like this:

prefix=/usr/local

exec_prefix=/usr/local/bin

libdir=/usr/local/lib64

includedir=/usr/local/include

Name: mcsapi

Version: 1.1.5-8d8b726

Description: A C++ library to connect to MariaDB ColumnStore

Libs: -L${libdir} -luv -lxml2 -lsnappy -lmcsapi

Cflags: -I${includedir}

As the software is installed in default locations, this works anyway, despite the output from --libs and --cflags to pkg-config being incorrect.