patch 8.0.0179: cannot have a local value for 'formatprg'

Problem:    'formatprg' is a global option but the value may depend on the
            type of buffer. (Sung Pae)
Solution:   Make 'formatprg' global-local. (closes #1380)
diff --git a/src/option.h b/src/option.h
index 13acabf..0ad2fef 100644
--- a/src/option.h
+++ b/src/option.h
@@ -1029,6 +1029,7 @@
     , BV_EP
     , BV_ET
     , BV_FENC
+    , BV_FP
 #ifdef FEAT_EVAL
     , BV_BEXPR
     , BV_FEX