* support old environments without libgen.h (ancient GNU/Linux)

and stdbool.h (ancient GNU/Linux; NetBSD® 1.6.1)
* __dead must come after, not before, to accomodate gcc 2.7.2.3

Build.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-# $MirOS: src/bin/mksh/Build.sh,v 1.127 2007/01/17 22:35:09 tg Exp $
+# $MirOS: src/bin/mksh/Build.sh,v 1.128 2007/01/17 22:51:45 tg Exp $
 #-
 # Environment: CC, CFLAGS, CPP, CPPFLAGS, LDFLAGS, LIBS, NOWARN, NROFF
 # With -x (cross compile): TARGET_OS (default: uname -s)
@@ -297,6 +297,16 @@ ac_test sys_param_h '' '<sys/param.h>' <<'EOF'
 	int main(void) { return (0); }
 EOF
 
+ac_test libgen_h '' '<libgen.h>' <<'EOF'
+	#include <libgen.h>
+	int main(void) { return (0); }
+EOF
+
+ac_test stdbool_h '' '<stdbool.h>' <<'EOF'
+	#include <stdbool.h>
+	int main(void) { return (0); }
+EOF
+
 #
 # Environment: signals
 #