Revert "Revert "Turn off extern templates for most uses.""

The bionic tests on x86_64 are very unhappy about this:

external/gtest/include/gtest/gtest-printers.h:245: error: undefined reference to 'std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(__float128)'
external/gtest/include/gtest/gtest-printers.h:245: error: undefined reference to 'std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(__float128)'
external/gtest/include/gtest/gtest-printers.h:245: error: undefined reference to 'std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(__float128)'
external/gtest/include/gtest/gtest-printers.h:245: error: undefined reference to 'std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(__float128)'

I'll investigate tomorrow, but for now it's easiest to just revert.

This reverts commit 98c4e404ca8c524c54b4e7ede97b807355422b53.
Change-Id: I4c4e83be2ca465069734c54f4dcfa539916d35e4
diff --git a/src/locale.cpp b/src/locale.cpp
index f21e35d..e626528 100644
--- a/src/locale.cpp
+++ b/src/locale.cpp
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#define _LIBCPP_EXTERN_TEMPLATE(...) extern template __VA_ARGS__;
+
 // On Solaris, we need to define something to make the C99 parts of localeconv
 // visible.
 #ifdef __sun__