Allow to cross-compile exe2coff

Patch from Pali <pali@pali.im>.

Author: Eli-Zaretskii

src/stub/exe2coff.c

@@ -5,10 +5,12 @@
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <string.h>
-#include <io.h>
 #include <unistd.h>
 #include <ctype.h>
 
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
 
 static void
 exe2aout(char *fname)

src/stub/makefile

@@ -22,6 +22,7 @@ all :: native \
 native :: \
 	$(HOSTBIN)/stubedit.exe \
 	$(HOSTBIN)/stubify.exe \
+	$(HOSTBIN)/exe2coff.exe \
 	$(INC)/stubinfo.h \
 	$E
 	$(NOP)
@@ -68,6 +69,9 @@ $(HOSTBIN)/stubify.exe : stubify.c stub.h
 $(HOSTBIN)/stubedit.exe : stubedit.c $(INC)/stubinfo.h
 	$(GCC) stubedit.c -o $@
 
+$(HOSTBIN)/exe2coff.exe : exe2coff.c
+	$(GCC) exe2coff.c -o $@
+
 ./stub2inc.exe : stub2inc.c
 	$(GCC) stub2inc.c -o $@