Win32: defined pdb path.

By default, MSVC uses vc<version>.pdb in the current directory.
With the "-Fd" switch it is directed to be in the objs directory instead.

auto/cc/msvc

@@ -108,7 +108,7 @@ CORE_LIBS="$CORE_LIBS kernel32.lib user32.lib"
 # msvc under Wine issues
 # C1902: Program database manager mismatch; please check your installation
 if [ -z "$NGX_WINE" ]; then
-   CFLAGS="$CFLAGS -Zi"
+   CFLAGS="$CFLAGS -Zi -Fd$NGX_OBJS/nginx.pdb"
    CORE_LINK="$CORE_LINK -debug"
 fi