Failure to initialize crypto is fatal

- Almost nothing works if crypto fails to initialize for whatever reason,
  check and propagate rpmInitCrypto() failure from rpmReadConfigFiles().
- Logging the error left for individual crypto backends to let them
  identify themselves: beecrypt requires no initialization whatsoever
  so it cannot fail at all, but NSS can fail in a number of entertaining
  ways due to missing dlopen()'ed bits and pieces, this should help
  avoiding wild-goose chases in such cases (RhBug:909627, RhBug:909618...)

lib/rpmrc.c

@@ -1607,7 +1607,8 @@ int rpmReadConfigFiles(const char * file, const char * target)
 {
     /* Force preloading of dlopen()'ed libraries in case we go chrooting */
     (void) gethostbyname("localhost");
-    (void) rpmInitCrypto();
+    if (rpmInitCrypto())
+	return -1;
 
     /* Preset target macros */
    	/* FIX: target can be NULL */

rpmio/digest_nss.c

@@ -62,6 +62,7 @@ int rpmInitCrypto(void)
 #else
 	if (NSS_NoDB_Init(NULL) != SECSuccess) {
 #endif
+	    rpmlog(RPMLOG_ERR, _("Failed to initialize NSS library\n"));
 	    rc = -1;
 	} else {
 	    _crypto_initialized = 1;