[DO NOT MERGE] build: Delete source fortification logic

CMakeLists.txt

@@ -481,24 +481,6 @@ if(ENABLE_HARDENING)
     try_append_linker_flag("/NXCOMPAT" TARGET hardening_interface)
   else()
 
-    # _FORTIFY_SOURCE requires that there is some level of optimization,
-    # otherwise it does nothing and just creates a compiler warning.
-    try_append_cxx_flags("-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3"
-      RESULT_VAR cxx_supports_fortify_source
-      SOURCE "int main() {
-              # if !defined __OPTIMIZE__ || __OPTIMIZE__ <= 0
-                #error
-              #endif
-              }"
-    )
-    if(cxx_supports_fortify_source)
-      target_compile_options(hardening_interface INTERFACE
-        -U_FORTIFY_SOURCE
-        -D_FORTIFY_SOURCE=3
-      )
-    endif()
-    unset(cxx_supports_fortify_source)
-
     try_append_cxx_flags("-Wstack-protector" TARGET hardening_interface SKIP_LINK)
     try_append_cxx_flags("-fstack-protector-all" TARGET hardening_interface)
     try_append_cxx_flags("-fcf-protection=full" TARGET hardening_interface)