Move -DLINK_LIST_THREADSAFE into Common.make from Common.gmake

Use -f (file) test instead of -e (exists) to locate soundcard.h since
Solaris' sh internal test apparently doesn't support -e.

src/xpdev/Common.gmake

@@ -20,4 +20,3 @@ endif
 ifeq ($(os),linux)	# Linux
  XPDEV-MT_LIBS	+=	-lpthread
 endif
-MT_CFLAGS += -DLINK_LIST_THREADSAFE

src/xpdev/Common.make

@@ -5,7 +5,7 @@ XPDEV-MT_LIB		=	$(XPDEV_SRC)$(DIRSEP)$(LIBODIR)$(DIRSEP)$(LIBPREFIX)xpdev_mt$(LI
 
 XPDEV_CFLAGS	=	-I$(XPDEV_SRC)
 XPDEV_LDFLAGS	=	-L$(XPDEV_SRC)$(DIRSEP)$(LIBODIR)
-XPDEV-MT_CFLAGS	=	$(XPDEV_CFLAGS)
+XPDEV-MT_CFLAGS	=	$(XPDEV_CFLAGS) -DLINK_LIST_THREADSAFE
 XPDEV-MT_LDFLAGS=	$(XPDEV_LDFLAGS)
 XPDEV_LIBS	=	$(UL_PRE)xpdev$(UL_SUF)
 XPDEV-MT_LIBS	=	$(UL_PRE)xpdev_mt$(UL_SUF)

src/xpdev/GNUmakefile

@@ -6,7 +6,7 @@ ifdef XP_SEM
 endif
 MTOBJS	+=	$(MTOBJODIR)$(DIRSEP)xpevent$(OFILE)
 
-CFLAGS	+=	-DSOUNDCARD_H_IN=$(shell if [ -e /usr/include/sys/soundcard.h ] ; then echo SYS ; elif [ -e /usr/include/soundcard.h ] ; then echo INCLUDE ; elif [ -e /usr/include/linux/soundcard.h ] ; then echo LINUX ; else echo NONE ; fi) -I.
+CFLAGS	+=	-DSOUNDCARD_H_IN=$(shell if [ -f /usr/include/sys/soundcard.h ] ; then echo SYS ; elif [ -f /usr/include/soundcard.h ] ; then echo INCLUDE ; elif [ -f /usr/include/linux/soundcard.h ] ; then echo LINUX ; else echo NONE ; fi) -I.
 
 # Executable Build Rule
 $(WRAPTEST): $(OBJODIR)/wraptest.o $(DEPS)