make openbsd compile with NO_UI=1

vm/Config.openbsd

@@ -1,4 +1,5 @@
 include vm/Config.unix
 PLAF_DLL_OBJS += vm/os-genunix.o vm/os-openbsd.o
+CC = egcc
 CFLAGS += -export-dynamic
 LIBS = -L/usr/local/lib/ -lm $(X11_UI_LIBS)

vm/os-openbsd-x86.32.h

@@ -1,7 +1,10 @@
+#include <i386/signal.h>
+
 INLINE void *openbsd_stack_pointer(void *uap)
 {
-	ucontext_t *ucontext = (ucontext_t *)uap;
-	return (void *)ucontext->sc_esp;
+	struct sigcontext *sc = (struct sigcontext*) uap;
+	return (void *)sc->sc_esp;
 }
 
 #define ucontext_stack_pointer openbsd_stack_pointer
+#define UAP_PROGRAM_COUNTER(uap) (((struct sigcontext*)(uap))->sc_eip)

vm/os-openbsd.h

@@ -1,2 +1,6 @@
 #define UNKNOWN_TYPE_P(file) ((file)->d_type == DT_UNKNOWN)
 #define DIRECTORY_P(file) ((file)->d_type == DT_DIR)
+
+#ifndef environ
+	extern char **environ;
+#endif