nanodbc: Remove extra CXX flags from the build

nanodbc was overriding the C++ standard library being used, which would
break builds with clang. Additionally, adding Werror unconditionally in
production code is a bad idea because different compiler versions can
change/add warnings and then break the code.

thirdparty/nanodbc/CMakeLists.txt

@@ -26,20 +26,7 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 message(STATUS "nanodbc compile: C++${CMAKE_CXX_STANDARD}")
 
 if(CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR CMAKE_COMPILER_IS_GNUCXX)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wnarrowing -Werror")
   include(CheckCXXCompilerFlag)
-
-  if(NOT NANODBC_DISABLE_LIBCXX)
-    check_cxx_compiler_flag("-stdlib=libc++" CXX_SUPPORTS_STDLIB)
-    if(CXX_SUPPORTS_STDLIB)
-      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")
-      set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -stdlib=libc++")
-      set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -stdlib=libc++")
-      set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -stdlib=libc++")
-    endif()
-    set(NANODBC_DISABLE_LIBCXX ${NANODBC_DISABLE_LIBCXX} CACHE BOOL "Do not use libc++, if available." FORCE)
-  endif()
-  message(STATUS "nanodbc build: Disable linking libc++ - ${NANODBC_DISABLE_LIBCXX}")
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "Intel")
     string(REGEX REPLACE "[/-]W[0-4]" "/W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
     if (NOT (CMAKE_VERSION VERSION_LESS 3.6.0)) # Compiler features for Intel in CMake 3.6+
@@ -202,4 +189,4 @@ endif()
 if(NANODBC_ENABLE_UNICODE)
   add_compile_definitions(NANODBC_ENABLE_UNICODE)
   target_compile_definitions(nanodbc PUBLIC NANODBC_ENABLE_UNICODE)
-endif()
+endif()