VS: Populate `/JMC-` flag table entry for v143

Apply the change from commit 049410c0b6 (VS: Populate `/JMC-` flag table
entry for v142, 2019-01-24, v3.14.0-rc1~74^2~6) to the v143 flag table.

Templates/MSBuild/FlagTables/v143_CL.json

@@ -742,6 +742,13 @@
     "value": "true",
     "flags": []
   },
+  {
+    "name": "SupportJustMyCode",
+    "switch": "JMC-",
+    "comment": "Support Just My Code Debugging",
+    "value": "false",
+    "flags": []
+  },
   {
     "name": "SupportJustMyCode",
     "switch": "JMC",