Enable release debug symbols for our from_cpython code

We already have this for the rest of our code, but it
wasn't enabled for C files.

CMakeLists.txt

@@ -177,7 +177,7 @@ if(ENABLE_OPROFILE)
   set(OPTIONAL_LIBRARIES ${OPTIONAL_LIBRARIES} opagent)
 endif()
 
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Werror -Wreturn-type -Wno-sign-compare -Wno-unused -Wno-unused-parameter -fno-omit-frame-pointer")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Werror -Wreturn-type -Wno-sign-compare -Wno-unused -Wno-unused-parameter -fno-omit-frame-pointer -g")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CMAKE_C_FLAGS} -std=c++11 -fno-rtti -fexceptions -fvisibility-inlines-hidden -ffunction-sections -fdata-sections -Woverloaded-virtual -Wno-invalid-offsetof -Wcast-qual -Wno-sign-conversion -Wnon-virtual-dtor -Winit-self -Wmissing-include-dirs -Wstrict-overflow=5 -Wpointer-arith -Wtype-limits -Wwrite-strings -Wempty-body -Waggregate-return -Wmissing-field-initializers -Wredundant-decls -Winline -Wint-to-pointer-cast -Wlong-long -Wvla -Wno-attributes -g")
 
 set(CLANG_FLAGS "${CLANG_FLAGS} -Wimplicit-int -Wstrict-prototypes -Wold-style-definition -Wnested-externs -Wpointer-to-int-cast -Wno-mismatched-tags -Wno-extern-c-compat")