Fix regressions on dynamic buildrequires cli switches (RhBug:2078744)

This effectively reverts commits b8935fb235
and ad8b9bd2ca and separating -br and -bd
from the normal build flow: these are so different from regular builds
and in particular, have special semantics wrt --nodeps that trying to
cram them into the normal flow only makes it far harder to read and
understand.

rpmbuild.c

@@ -663,16 +663,12 @@ int main(int argc, char *argv[])
 	/* fallthrough */
     case 'f':
 	ba->buildAmount |= RPMBUILD_CONF;
-	if ((buildChar == 'f') && shortCircuit)
-	    break;
-	/* fallthrough */
-    case 'r':
-    case 'd':
 	ba->buildAmount |= RPMBUILD_BUILDREQUIRES;
+	if (!noDeps) {
 	    ba->buildAmount |= RPMBUILD_DUMPBUILDREQUIRES;
-	if (!noDeps)
 	    ba->buildAmount |= RPMBUILD_CHECKBUILDREQUIRES;
-	if ((buildChar == 'r' || buildChar == 'd') && shortCircuit)
+	}
+	if ((buildChar == 'f') && shortCircuit)
 	    break;
 	/* fallthrough */
     case 'p':
@@ -681,6 +677,18 @@ int main(int argc, char *argv[])
     case 'l':
 	ba->buildAmount |= RPMBUILD_FILECHECK;
 	break;
+    case 'r':
+	/* fallthrough */
+    case 'd':
+	if (!shortCircuit)
+	    ba->buildAmount |= RPMBUILD_PREP;
+	ba->buildAmount |= RPMBUILD_BUILDREQUIRES;
+	ba->buildAmount |= RPMBUILD_DUMPBUILDREQUIRES;
+	if (!noDeps)
+	    ba->buildAmount |= RPMBUILD_CHECKBUILDREQUIRES;
+	if (buildChar == 'd')
+	    break;
+	/* fallthrough */
     case 's':
 	ba->buildAmount |= RPMBUILD_PACKAGESOURCE;
 	break;

tests/rpmbuild.at

@@ -1707,6 +1707,38 @@ runroot rpmbuild \
 )
 AT_CLEANUP
 
+# Test that -br creates an src.rpm on success
+AT_SETUP([rpmbuild -br success])
+AT_KEYWORDS([build])
+AT_CHECK([
+RPMDB_INIT
+
+runroot rpmbuild \
+  -br  /data/SPECS/mini.spec
+],
+[0],
+[Wrote: /build/SRPMS/mini-1-1.src.rpm
+],
+[],
+)
+AT_CLEANUP
+
+# Test that -br creates an src.rpm on success
+AT_SETUP([rpmbuild -br success])
+AT_KEYWORDS([build])
+AT_CHECK([
+RPMDB_INIT
+
+runroot rpmbuild \
+  -br  /data/SPECS/mini.spec
+],
+[0],
+[Wrote: /build/SRPMS/mini-1-1.src.rpm
+],
+[],
+)
+AT_CLEANUP
+
 # ------------------------------
 # Check dynamic build requires
 AT_SETUP([rpmbuild -bd with errors])