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

diff --git a/auto/cc/msvc b/auto/cc/msvc
index 8257252..68435ff 100644
--- a/auto/cc/msvc
+++ b/auto/cc/msvc
@@ -108,7 +108,7 @@
 # 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