tests: Fix signalling race condition in TPM tests

This patch fixes a race condition and test failure where the main process
waits for the signal of a thread but the thread already sent that signal
via a condition. Since these signals are non-sticky, we need to introduce a
separate variable to make this signal sticky.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

tests/tpm-emu.h

@@ -26,6 +26,7 @@ struct tpm_hdr {
 typedef struct TestState {
     GMutex data_mutex;
     GCond data_cond;
+    bool data_cond_signal;
     SocketAddress *addr;
     QIOChannel *tpm_ioc;
     GThread *emu_tpm_thread;