Separated Win16 (USER) and Win32 (MPR) network routines.
Moved implementation of MPR to dlls/mpr/.
Added proper headers and stubs for missing MPR routines.

diff --git a/configure.in b/configure.in
index 5ad2c49..d61acfb 100644
--- a/configure.in
+++ b/configure.in
@@ -802,6 +802,7 @@
 dlls/imagehlp/Makefile
 dlls/imm32/Makefile
 dlls/lzexpand/Makefile
+dlls/mpr/Makefile
 dlls/msacm/Makefile
 dlls/msacm32/Makefile
 dlls/msnet32/Makefile