bc: move fflush to the _actual_ execution loop

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/miscutils/bc.c b/miscutils/bc.c
index 24d1ebb..c92f6f8 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -6875,6 +6875,8 @@
 			RETURN_STATUS(s);
 		}
 
+		fflush_and_check();
+
 		// If the stack has changed, pointers may be invalid.
 		ip = bc_vec_top(&G.prog.stack);
 		func = bc_program_func(ip->func);
@@ -6920,7 +6922,6 @@
 			bc_program_reset();
 			break;
 		}
-		fflush_and_check();
 	}
 
 	dbg_lex_done("%s:%d done", __func__, __LINE__);