Autogen: Fix multi-config generated file issue
The default config was an empty string when a multi-config
generator is used. An if check was added for those situations.
If a source file has a specific config configuration, it is used with $<CONFIG>
in the multi-config
generator usage.
The redundant cmake_autogen
process execution was optimized for non-CROSS_CONFIGS
usage. It was executed three times for each config although only one of them is needed.
Fixes: #24848 (closed)
Edited by Orkun Tokdemir