cmake: add -Wl,--no-undefined to GCC linker flags

This way unresolved symbols will be detected when linking the shared
library version.

CMakeLists.txt

@@ -340,6 +340,12 @@ if(USE_GCC OR USE_CLANG)
   if(HAVE_GCC_WSHADOW)
     list(APPEND EXTRA_CFLAGS "-Wshadow")
   endif()
+
+  set(CMAKE_REQUIRED_FLAGS "-Wl,--no-undefined")
+  check_c_compiler_flag("" HAVE_NO_UNDEFINED)
+  if(HAVE_NO_UNDEFINED)
+    list(APPEND EXTRA_LDFLAGS "-Wl,--no-undefined")
+  endif()
 endif()
 
 if(ASSEMBLY)