patch 8.0.0902: cannot specify directory or environment for a job

Problem:    Cannot specify directory or environment for a job.
Solution:   Add the "cwd" and "env" arguments to job options. (Yasuhiro
            Matsumoto, closes #1160)
diff --git a/src/structs.h b/src/structs.h
index 618cabf..16f2cc1 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1686,7 +1686,9 @@
 #define JO2_ERR_MSG	    0x0002	/* "err_msg" (JO_OUT_ << 1) */
 #define JO2_TERM_NAME	    0x0004	/* "term_name" */
 #define JO2_TERM_FINISH	    0x0008	/* "term_finish" */
-#define JO2_ALL		    0x000F
+#define JO2_ENV		    0x0010	/* "env" */
+#define JO2_CWD		    0x0020	/* "cwd" */
+#define JO2_ALL		    0x003F
 
 #define JO_MODE_ALL	(JO_MODE + JO_IN_MODE + JO_OUT_MODE + JO_ERR_MODE)
 #define JO_CB_ALL \
@@ -1738,6 +1740,9 @@
     int		jo_id;
     char_u	jo_soe_buf[NUMBUFLEN];
     char_u	*jo_stoponexit;
+    dict_T	*jo_env;	/* environment variables */
+    char_u	jo_cwd_buf[NUMBUFLEN];
+    char_u	*jo_cwd;
 
 #ifdef FEAT_TERMINAL
     /* when non-zero run the job in a terminal window of this size */