Remove extraneous leading whitespace in Windows build script.

Apparently, at least some versions of Microsoft's shell fail on variable
assignments that have leading whitespace.  This instance, introduced in
commit 680513ab7, managed to escape notice for awhile because it's only
invoked if building with OpenSSL.  Per bug #14185 from Torben Dannhauer.

Report: <20160613140119.5798.78501@wrigleys.postgresql.org>

src/interfaces/libpq/win32.mak

@@ -167,8 +167,9 @@ LIB32_OBJS= \
 	"$(INTDIR)\win32error.obj" \
 	"$(INTDIR)\win32setlocale.obj" \
 	"$(INTDIR)\pthread-win32.obj"
+
 !IFDEF USE_OPENSSL
-	LIB32_OBJS=$(LIB32_OBJS) "$(INTDIR)\fe-secure-openssl.obj"
+LIB32_OBJS=$(LIB32_OBJS) "$(INTDIR)\fe-secure-openssl.obj"
 !ENDIF