Make encoding loading not issue warning

Instead of relying on setting an unsetting ruby_verbose, which is
not thread-safe, restructure require_internal and load_lock to
accept a warn argument for whether to warn, and add
rb_require_internal_silent to require without warnings.  Use
rb_require_internal_silent when loading encoding.

Note this does not modify ruby_debug and errinfo handling, those
remain thread-unsafe.

Also silent requires when loading transcoders.

encoding.c

@@ -797,11 +797,12 @@ rb_enc_get_from_index(int index)
     return must_encindex(index);
 }
 
+int rb_require_internal_silent(VALUE fname);
+
 static int
 load_encoding(const char *name)
 {
     VALUE enclib = rb_sprintf("enc/%s.so", name);
-    VALUE verbose = ruby_verbose;
     VALUE debug = ruby_debug;
     VALUE errinfo;
     char *s = RSTRING_PTR(enclib) + 4, *e = RSTRING_END(enclib) - 3;
@@ -814,11 +815,9 @@ load_encoding(const char *name)
 	++s;
     }
     enclib = rb_fstring(enclib);
-    ruby_verbose = Qfalse;
     ruby_debug = Qfalse;
     errinfo = rb_errinfo();
-    loaded = rb_require_internal(enclib);
-    ruby_verbose = verbose;
+    loaded = rb_require_internal_silent(enclib);
     ruby_debug = debug;
     rb_set_errinfo(errinfo);
 

load.c

@@ -767,7 +767,7 @@ rb_f_load(int argc, VALUE *argv, VALUE _)
 }
 
 static char *
-load_lock(const char *ftptr)
+load_lock(const char *ftptr, bool warn)
 {
     st_data_t data;
     st_table *loading_tbl = get_loading_table();
@@ -787,7 +787,7 @@ load_lock(const char *ftptr)
 	(*init)();
 	return (char *)"";
     }
-    if (RTEST(ruby_verbose)) {
+    if (warn) {
 	VALUE warning = rb_warning_string("loading in progress, circular require considered harmful - %s", ftptr);
 	rb_backtrace_each(rb_str_append, warning);
 	rb_warning("%"PRIsVALUE, warning);
@@ -1050,7 +1050,7 @@ rb_ext_ractor_safe(bool flag)
  * >1: exception
  */
 static int
-require_internal(rb_execution_context_t *ec, VALUE fname, int exception)
+require_internal(rb_execution_context_t *ec, VALUE fname, int exception, bool warn)
 {
     volatile int result = -1;
     rb_thread_t *th = rb_ec_thread_ptr(ec);
@@ -1084,7 +1084,7 @@ require_internal(rb_execution_context_t *ec, VALUE fname, int exception)
         path = saved_path;
 
 	if (found) {
-            if (!path || !(ftptr = load_lock(RSTRING_PTR(path)))) {
+            if (!path || !(ftptr = load_lock(RSTRING_PTR(path), warn))) {
 		result = 0;
 	    }
 	    else if (!*ftptr) {
@@ -1149,11 +1149,18 @@ require_internal(rb_execution_context_t *ec, VALUE fname, int exception)
     return result;
 }
 
+int
+rb_require_internal_silent(VALUE fname)
+{
+    rb_execution_context_t *ec = GET_EC();
+    return require_internal(ec, fname, 1, false);
+}
+
 int
 rb_require_internal(VALUE fname)
 {
     rb_execution_context_t *ec = GET_EC();
-    return require_internal(ec, fname, 1);
+    return require_internal(ec, fname, 1, RTEST(ruby_verbose));
 }
 
 int
@@ -1162,7 +1169,7 @@ ruby_require_internal(const char *fname, unsigned int len)
     struct RString fake;
     VALUE str = rb_setup_fake_str(&fake, fname, len, 0);
     rb_execution_context_t *ec = GET_EC();
-    int result = require_internal(ec, str, 0);
+    int result = require_internal(ec, str, 0, RTEST(ruby_verbose));
     rb_set_errinfo(Qnil);
     return result == TAG_RETURN ? 1 : result ? -1 : 0;
 }
@@ -1171,7 +1178,7 @@ VALUE
 rb_require_string(VALUE fname)
 {
     rb_execution_context_t *ec = GET_EC();
-    int result = require_internal(ec, fname, 1);
+    int result = require_internal(ec, fname, 1, RTEST(ruby_verbose));
 
     if (result > TAG_RETURN) {
         EC_JUMP_TAG(ec, result);

transcode.c

@@ -376,6 +376,8 @@ transcode_search_path(const char *sname, const char *dname,
     return pathlen; /* is -1 if not found */
 }
 
+int rb_require_internal_silent(VALUE fname);
+
 static const rb_transcoder *
 load_transcoder_entry(transcoder_entry_t *entry)
 {
@@ -393,7 +395,7 @@ load_transcoder_entry(transcoder_entry_t *entry)
         memcpy(path + sizeof(transcoder_lib_prefix) - 1, lib, len);
         rb_str_set_len(fn, total_len);
         OBJ_FREEZE(fn);
-        rb_require_string(fn);
+        rb_require_internal_silent(fn);
     }
 
     if (entry->transcoder)