patch 8.1.1275: cannot navigate to errors before/after the cursor

Problem:    Cannot navigate to errors before/after the cursor.
Solution:   Add the :cbefore and :cafter commands. (Yegappan Lakshmanan,
            closes #4340)
diff --git a/src/ex_cmds.h b/src/ex_cmds.h
index 58aa8c3..9e420b3 100644
--- a/src/ex_cmds.h
+++ b/src/ex_cmds.h
@@ -266,6 +266,9 @@
 EX(CMD_caddfile,	"caddfile",	ex_cfile,
 			TRLBAR|FILE1,
 			ADDR_NONE),
+EX(CMD_cafter,		"cafter",	ex_cbelow,
+			RANGE|COUNT|TRLBAR,
+			ADDR_UNSIGNED),
 EX(CMD_call,		"call",		ex_call,
 			RANGE|NEEDARG|EXTRA|NOTRLCOM|SBOXOK|CMDWIN,
 			ADDR_LINES),
@@ -275,6 +278,9 @@
 EX(CMD_cbuffer,		"cbuffer",	ex_cbuffer,
 			BANG|RANGE|WORD1|TRLBAR,
 			ADDR_OTHER),
+EX(CMD_cbefore,		"cbefore",	ex_cbelow,
+			RANGE|COUNT|TRLBAR,
+			ADDR_UNSIGNED),
 EX(CMD_cbelow,		"cbelow",	ex_cbelow,
 			RANGE|COUNT|TRLBAR,
 			ADDR_UNSIGNED),
@@ -749,12 +755,18 @@
 EX(CMD_laddfile,	"laddfile",	ex_cfile,
 			TRLBAR|FILE1,
 			ADDR_NONE),
+EX(CMD_lafter,		"lafter",	ex_cbelow,
+			RANGE|COUNT|TRLBAR,
+			ADDR_UNSIGNED),
 EX(CMD_later,		"later",	ex_later,
 			TRLBAR|EXTRA|NOSPC|CMDWIN,
 			ADDR_NONE),
 EX(CMD_lbuffer,		"lbuffer",	ex_cbuffer,
 			BANG|RANGE|WORD1|TRLBAR,
 			ADDR_OTHER),
+EX(CMD_lbefore,		"lbefore",	ex_cbelow,
+			RANGE|COUNT|TRLBAR,
+			ADDR_UNSIGNED),
 EX(CMD_lbelow,		"lbelow",	ex_cbelow,
 			RANGE|COUNT|TRLBAR,
 			ADDR_UNSIGNED),