py: Use shorter, static error msgs when ERROR_REPORTING_TERSE enabled.

Going from MICROPY_ERROR_REPORTING_NORMAL to
MICROPY_ERROR_REPORTING_TERSE now saves 2020 bytes ROM for ARM Thumb2,
and 2200 bytes ROM for 32-bit x86.

This is about a 2.5% code size reduction for bare-arm.
diff --git a/py/parsenum.c b/py/parsenum.c
index f7f43ac..bb88eb7 100644
--- a/py/parsenum.c
+++ b/py/parsenum.c
@@ -138,7 +138,13 @@
     }
 
 value_error:
-    nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "invalid syntax for integer with base %d: '%s'", base, str));
+    if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
+            "invalid syntax for integer"));
+    } else {
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError,
+            "invalid syntax for integer with base %d: '%s'", base, str));
+    }
 }
 
 typedef enum {