CMake: Fix DLL install directory in mingw

[Biswa96]

This installs DLL in 'bin' directory instead of 'lib' by default.
In mingw environment, all DLLs and EXEs are installed in 'bin'
and static & import libraries are installed in 'lib' directory.
This does not affect other environment because the 'RUNTIME'
and 'LIBRARY' targets are automatically set by cmake. See
https://cmake.org/cmake/help/latest/command/install.html

Fixes #502

[Biswa96]

This also fixes the generated cmake file as following.

--- a/lib/cmake/CLBlast/CLBlastConfig-release.cmake
+++ b/lib/cmake/CLBlast/CLBlastConfig-release.cmake
@@ -10,11 +10,11 @@
 set_target_properties(clblast PROPERTIES
   IMPORTED_IMPLIB_RELEASE "${_IMPORT_PREFIX}/lib/libclblast.dll.a"
   IMPORTED_LINK_INTERFACE_LIBRARIES_RELEASE "/ucrt64/lib/libOpenCL.dll.a"
-  IMPORTED_LOCATION_RELEASE "${_IMPORT_PREFIX}/lib/libclblast.dll"
+  IMPORTED_LOCATION_RELEASE "${_IMPORT_PREFIX}/bin/libclblast.dll"
   )
 
 list(APPEND _cmake_import_check_targets clblast )
-list(APPEND _cmake_import_check_files_for_clblast "${_IMPORT_PREFIX}/lib/libclblast.dll.a" "${_IMPORT_PREFIX}/lib/libclblast.dll" )
+list(APPEND _cmake_import_check_files_for_clblast "${_IMPORT_PREFIX}/lib/libclblast.dll.a" "${_IMPORT_PREFIX}/bin/libclblast.dll" )
 
 # Commands beyond this point should not need to know the version.
 set(CMAKE_IMPORT_FILE_VERSION)

[bandoti]

Nice! Thank you.

[CNugteren]

Great, thanks for fixing this issue!

One minor comment, if you would be so kind to add a note about this fix between line 2 and 3 of the CHANGELOG (https://github.com/CNugteren/CLBlast/blob/master/CHANGELOG#L2C1-L2C69).

Thanks

[Biswa96]

Done.