Remove PkgConfig dependence on Windows

PkgConfig works properly only on Linux. On Windows, it is part of the MSYS2 platform and there is no guarantee that it works properly; it is also not necessary.

Instead of using PkgConfig, a CMake module FindPkgVersionWin is introduced to find the version of a package from a config file.

find_pkg_version_win function is used to find the version of cerf package under Windows.

Related to issue #133 (closed)

cmake/commons/FindPkgVersionWin.cmake

@@ -71,7 +71,7 @@ function(find_pkg_version_win libname conffile paths output_var)
     string(TOLOWER "${_conf}" _conf_lc)
     string(REGEX MATCH "version[: \t]*([1-9.]+)" _rxmatch ${_conf_lc})
 
-    if(${CMAKE_MATCH_1})
+    if("${CMAKE_MATCH_1}")
         set(${_outvar} "${CMAKE_MATCH_1}" PARENT_SCOPE)
     endif ()