Merge pull request ceph#44831 from adamemerson/wip-prepend

build: PREPEND -Og, not APPEND

Reviewed-by: Kefu Chai <tchaikov@gmail.com>
Reviewed-by: Matt Benjamin <mbenjami@redhat.com>

Author: adamemerson

src/CMakeLists.txt

@@ -121,7 +121,7 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL GNU)
   else()
     string(APPEND CMAKE_EXE_LINKER_FLAGS " -rdynamic")
   endif()
-  string(APPEND CMAKE_CXX_FLAGS_DEBUG " -Og")
+  string(PREPEND CMAKE_CXX_FLAGS_DEBUG "-Og ")
   add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Wstrict-null-sentinel>)
   add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Woverloaded-virtual>)
   add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-fno-new-ttp-matching>)
@@ -135,7 +135,7 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL GNU)
 elseif(CMAKE_CXX_COMPILER_ID STREQUAL Clang)
   set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_EXPORTS_C_FLAG}")
   string(APPEND CMAKE_LINKER_FLAGS " -rdynamic -export-dynamic ${CMAKE_EXE_EXPORTS_C_FLAG}")
-  string(APPEND CMAKE_CXX_FLAGS_DEBUG " -g")
+  string(PREPEND CMAKE_CXX_FLAGS_DEBUG "-g ")
   add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Wno-inconsistent-missing-override>)
   add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Wno-mismatched-tags>)
   add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Wno-unused-private-field>)