try to link symlink and use a define on error
fixes compiling with Minimalist GNU win32 (cross) compiler 4.2.1, which
defines symlink, but doesn't implement it.
diff --git a/libasn1compiler/asn1c_save.c b/libasn1compiler/asn1c_save.c
index d71db19..f3cfcdf 100644
--- a/libasn1compiler/asn1c_save.c
+++ b/libasn1compiler/asn1c_save.c
@@ -6,6 +6,10 @@
#include "asn1c_save.h"
#include "asn1c_out.h"
+#ifndef HAVE_SYMLINK
+#define symlink(a,b) (errno=ENOSYS, -1)
+#endif
+
#define HINCLUDE(s) \
((arg->flags & A1C_INCLUDES_QUOTED) \
? fprintf(fp_h, "#include \"%s\"\n", s) \