Move external instantiation for __vector_base_common to vector.cpp

Previously the explicit instantiation for this was in locale.cpp,
but that didn't make much sense. This patch creates a new vector.cpp
source file to contain the explicit instantiation.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@305442 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index fe45f5a..f04ef82 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -1,6 +1,7 @@
 set(LIBCXX_LIB_CMAKEFILES_DIR "${CMAKE_CURRENT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}"  PARENT_SCOPE)
 
 # Get sources
+# FIXME: Don't use glob here
 file(GLOB LIBCXX_SOURCES ../src/*.cpp)
 if(WIN32)
   file(GLOB LIBCXX_WIN32_SOURCES ../src/support/win32/*.cpp)