janitor: do not rely on indirect inclusions of or from qemu-char.h

Various header files rely on qemu-char.h including qemu-config.h or
main-loop.h, but they really do not need qemu-char.h at all (particularly
interesting is the case of the block layer!).  Clean this up, and also
add missing inclusions of qemu-char.h itself.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

bt-host.c

@@ -21,6 +21,7 @@
 #include "qemu-char.h"
 #include "net.h"
 #include "bt-host.h"
+#include "main-loop.h"
 
 #ifndef _WIN32
 # include <errno.h>