Add patch for CAMD to fix incorrect func definition

The .fd file supplied with the CAMD SDK contains an incorrect function
definition for CreateMidiA(), which means that a stub is not generated
for the CreateMidi() function.

This also causes fd2sfd to emit the warning:
Warning: CreateMidiA gets 2 params and 1 regs!

Add a patch to fix the warning from fd2sfd and allow sfdc to generate a
stub for CreateMidi().

patches/camd/camd_lib.fd.diff

@@ -0,0 +1,11 @@
+--- camd/fd/camd_lib.fd.orig	2020-09-26 20:21:15.315420700 +0100
++++ camd/fd/camd_lib.fd	2020-09-26 20:21:27.785420700 +0100
+@@ -3,7 +3,7 @@
+ ##public
+ LockCAMD(locktype)(d0)
+ UnlockCAMD(lock)(a0)
+-CreateMidiA(name,tags)(a0)
++CreateMidiA(tags)(a0)
+ DeleteMidi(mi)(a0)
+ SetMidiAttrsA(mi,tags)(a0,a1)
+ GetMidiAttrsA(mi,tags)(a0,a1)

sdk/camd.sdk

@@ -2,6 +2,8 @@ Short: 	CAMD developer kit for MorphOS
 Version: 37.1
 Url: http://aminet.net/dev/c/camd-morphos-dev.lha
 
+patch : camd_lib.fd.diff
+
 camd/clib/camd_protos.h
 camd/fd/camd_lib.fd = camd.fd
 camd/midi/camd.h