Mark test_enc_conversion() as STRICT.

Reported-by: Jaime Casanova, using SQLsmith
Discussion: https://www.postgresql.org/message-id/20210402235337.GA4082@ahch-to

src/test/regress/input/create_function_1.source

@@ -80,7 +80,7 @@ CREATE FUNCTION test_opclass_options_func(internal)
 
 CREATE FUNCTION test_enc_conversion(bytea, name, name, bool, validlen OUT int, result OUT bytea)
     AS '@libdir@/regress@DLSUFFIX@', 'test_enc_conversion'
-    LANGUAGE C;
+    LANGUAGE C STRICT;
 
 -- Things that shouldn't work:
 

src/test/regress/output/create_function_1.source

@@ -70,7 +70,7 @@ CREATE FUNCTION test_opclass_options_func(internal)
     LANGUAGE C;
 CREATE FUNCTION test_enc_conversion(bytea, name, name, bool, validlen OUT int, result OUT bytea)
     AS '@libdir@/regress@DLSUFFIX@', 'test_enc_conversion'
-    LANGUAGE C;
+    LANGUAGE C STRICT;
 -- Things that shouldn't work:
 CREATE FUNCTION test1 (int) RETURNS int LANGUAGE SQL
     AS 'SELECT ''not an integer'';';