refactor: update compiler flag handling in CMake and ignore build log files

.gitignore

@@ -18,3 +18,5 @@ test_props.xml
 test_props2.xml
 test_boost.cpp
 .claude/settings.json
+build_output.log
+configure_output.log

CMakeLists.txt

@@ -19,14 +19,14 @@ endif()
 
 project(uLib)
 
-# Remove GCC-only flag injected by conda's CFLAGS/CXXFLAGS that clang doesn't support.
-# Must run after project() since that's when CMake initialises CMAKE_<LANG>_FLAGS from env.
+# Applica la flag SOLO se il compilatore è GCC
+if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    add_compile_options(-fno-merge-constants)
+endif()
+
+# Disabilita il warning se il compilatore è Clang (o AppleClang)
 if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-    foreach(_lang C CXX)
-        foreach(_var CMAKE_${_lang}_FLAGS CMAKE_${_lang}_FLAGS_RELEASE CMAKE_${_lang}_FLAGS_RELWITHDEBINFO CMAKE_${_lang}_FLAGS_DEBUG)
-            string(REPLACE "-fno-merge-constants" "" ${_var} "${${_var}}")
-        endforeach()
-    endforeach()
+    add_compile_options(-Wno-ignored-optimization-argument)
 endif()
 
 # CUDA Toolkit seems to be missing locally. Toggle ON if nvcc is made available.