Add missing support for new node fields

Commit b6fb534f added two new node fields but neglected to add copy and
comparison support for them, Mea culpa, should have checked for that.

per buildfarm animals with -DCOPY_PARSE_PLAN_TREES

src/backend/nodes/copyfuncs.c

@@ -3917,6 +3917,7 @@ _copyCreateForeignServerStmt(const CreateForeignServerStmt *from)
 	COPY_STRING_FIELD(version);
 	COPY_STRING_FIELD(fdwname);
 	COPY_NODE_FIELD(options);
+	COPY_SCALAR_FIELD(if_not_exists);
 
 	return newnode;
 }
@@ -3942,6 +3943,7 @@ _copyCreateUserMappingStmt(const CreateUserMappingStmt *from)
 	COPY_NODE_FIELD(user);
 	COPY_STRING_FIELD(servername);
 	COPY_NODE_FIELD(options);
+	COPY_SCALAR_FIELD(if_not_exists);
 
 	return newnode;
 }

src/backend/nodes/equalfuncs.c

@@ -1828,6 +1828,7 @@ _equalCreateForeignServerStmt(const CreateForeignServerStmt *a, const CreateFore
 	COMPARE_STRING_FIELD(version);
 	COMPARE_STRING_FIELD(fdwname);
 	COMPARE_NODE_FIELD(options);
+	COMPARE_SCALAR_FIELD(if_not_exists);
 
 	return true;
 }
@@ -1849,6 +1850,7 @@ _equalCreateUserMappingStmt(const CreateUserMappingStmt *a, const CreateUserMapp
 	COMPARE_NODE_FIELD(user);
 	COMPARE_STRING_FIELD(servername);
 	COMPARE_NODE_FIELD(options);
+	COMPARE_SCALAR_FIELD(if_not_exists);
 
 	return true;
 }