MinGW fixes (development)

The MinGW system() implementation appears to return the straight
return value instead of the waitpid() like result that more
normal systems return. Because of this just return the system()
result without processing for MinGW compilations.

Older version of the MinGW runtime (pre 3.14) just used the
underlying vsnprintf(). Which has some problems. The 3.14 version
has some nice improvements, but it has a sever bug when processing
"%*.*f", -1, -1, <some_real_value>.  Because of this we need to use
the underlying version without the enhancements for now.

snprintf prints %p differently than the other printf routines
so use _snprintf to get consistent results.

Only build the PDF files if both man and ps2pdf exist.

MinGW does not know about the z modifier for %d, %u, etc.

Add some missing Makefile check targets.

driver-vpi/Makefile.in

@@ -16,12 +16,9 @@
 #    59 Temple Place - Suite 330
 #    Boston, MA 02111-1307, USA
 #
-#ident "$Id: Makefile.in,v 1.7.2.1 2006/10/04 17:08:59 steve Exp $"
-#
-#
 SHELL = /bin/sh
 
-VERSION = 0.8.3
+VERSION = 0.9.devel
 
 prefix = @prefix@
 exec_prefix = @exec_prefix@
@@ -48,6 +45,8 @@ LDFLAGS = @LDFLAGS@
 
 all: iverilog-vpi@EXEEXT@
 
+check: all
+
 clean:
 	rm -f *.o config.h
 	rm -f iverilog-vpi@EXEEXT@