Fix GLIBCXX error on Linux by adjusting CMAKE_SYSTEM_NAME check

[ncvicchi]

Related issue
Close #441

Description

This PR resolves the GLIBCXX version error observed when running the Wazuh agent on Linux after installing the latest RPM package.

The issue was caused by the CMAKE_SYSTEM_NAME check being executed before the project() declaration in the CMakeLists.txt file, which prevented proper detection of the system type.

This fix adjusts the location of the CMAKE_SYSTEM_NAME check to ensure it is evaluated after the project is initialized.

Root Cause

The following condition was evaluated too early:

if(CMAKE_SYSTEM_NAME STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "Darwin")
    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -static-libstdc++")
endif()

As a result, the -static-libstdc++ linker flag was not applied correctly during the build process for Linux.