Changed test for -u switch in order to enable other wmake switches.

The var %MAKEFLAGS is only set in 3 cases: if set as environment
var or as macro definition from commandline, and either with the
-u or -ms switch. Since all these cases are unlikely for the average
user it should be safe to only test if %MAKEFLAGS is defined; this
has the benefit that now all other switches can be used again in
addition to the -u which was formerly not possible.

lib/Makefile.Watcom

@@ -80,7 +80,7 @@ LINK_ARG = $(OBJ_BASE)\dyn\wlink.arg
 LIB_ARG  = $(OBJ_BASE)\stat\wlib.arg
 
 # In order to process Makefile.inc wmake must be called with -u switch!
-!ifneq __MAKEOPTS__ -u
+!ifndef %MAKEFLAGS
 !error You MUST call wmake with the -u switch!
 !else
 !include Makefile.inc

src/Makefile.Watcom

@@ -67,7 +67,7 @@ OBJ_DIR  = WC_Win32.obj
 LINK_ARG = $(OBJ_DIR)\wlink.arg
 
 # In order to process Makefile.inc wmake must be called with -u switch!
-!ifneq __MAKEOPTS__ -u
+!ifndef %MAKEFLAGS
 !error You MUST call wmake with the -u switch!
 !else
 !include Makefile.inc