Fix Serial build on IRIX, remove the STDC_HEADERS manually defined macro

since it now works (egrep was missing previously, IIRC)

BasiliskII/src/Unix/configure.ac

@@ -493,8 +493,6 @@ irix*)
   ETHERSRC=ether_unix.cpp
   AUDIOSRC=Irix/audio_irix.cpp
   EXTRASYSSRCS=Irix/unaligned.c
-  dnl IRIX headers work fine, but somehow don't define or use "STDC_HEADERS"
-  DEFINES="$DEFINES -DCRTSCTS=CNEW_RTSCTS -DB230400=B115200 -DSTDC_HEADERS"
   LIBS="$LIBS -laudio"
   WANT_ESD=no
 

BasiliskII/src/Unix/serial_unix.cpp

@@ -51,6 +51,17 @@ extern "C" {
 #define MONITOR 0
 
 
+// IRIX missing or unsupported defines
+#ifdef sgi
+#ifndef CRTSCTS
+#define CRTSCTS CNEW_RTSCTS
+#endif
+#ifndef B230400
+#define B230400 B115200
+#endif
+#endif
+
+
 // Missing functions
 #ifndef HAVE_CFMAKERAW
 static int cfmakeraw(struct termios *termios_p)