py: Add compile option to enable/disable source line numbers.
diff --git a/unix/mpconfigport.h b/unix/mpconfigport.h
index 10abb8c..5eba0df 100644
--- a/unix/mpconfigport.h
+++ b/unix/mpconfigport.h
@@ -12,6 +12,7 @@
 #define MICROPY_DEBUG_PRINTERS      (1)
 #define MICROPY_ENABLE_REPL_HELPERS (1)
 #define MICROPY_ENABLE_LEXER_UNIX   (1)
+#define MICROPY_ENABLE_SOURCE_LINE  (1)
 #define MICROPY_ENABLE_FLOAT        (1)
 #define MICROPY_LONGINT_IMPL        (MICROPY_LONGINT_IMPL_LONGLONG)