#2 MSVC 2010 Express issues a C4231 warning in log4cxx headers

[Plamen Ivanov]

"warning C4231: nonstandard extension used : 'extern' before template explicit instantiation" in the following files:
log4cxx\consoleappender.h(75)
log4cxx\fileappender.h(219)
log4cxx\spi\configurator.h(57)

Does not seem to affect runtime.