Allow modification of install directory for module files

[awvwgk]

The install directory for the module files will default to $PREFIX/include/fortran_stdlib/<compiler-id> and is automatically exported for both CMake package files and pkg-config files.

A possible alternative would be to install in $PREFIX/lib/fortran_stdlib/<compiler-id> instead:

diff --git a/config/CMakeLists.txt b/config/CMakeLists.txt
index 430cef2..e4e2ec2 100644
--- a/config/CMakeLists.txt
+++ b/config/CMakeLists.txt
@@ -3,7 +3,7 @@
 option(
   CMAKE_INSTALL_MODULEDIR
   "Directory in prefix to install generated module files"
-  "${CMAKE_INSTALL_INCLUDEDIR}/${PROJECT_NAME}/${CMAKE_Fortran_COMPILER_ID}-${CMAKE_Fortran_COMPILER_VERSION}"
+  "${CMAKE_INSTALL_LIBDIR}/${PROJECT_NAME}/${CMAKE_Fortran_COMPILER_ID}-${CMAKE_Fortran_COMPILER_VERSION}"
 )
 
 # Export a pkg-config file

[jvdp1]

OK from my side

[milancurcic]

I tried it, it works. Thanks!