Don't compile dynamic linking code into non-PIC version of libc. NFC (#18638)

Replaces #18637

Author: sbc100

src/library_dylink.js

@@ -240,12 +240,18 @@ var LibraryDylink = {
   _emscripten_dlopen_js__deps: [function() { error(dlopenMissingError); }],
   _dlsym_js__deps: [function() { error(dlopenMissingError); }],
   _dlsym_catchup_js__deps: [function() { error(dlopenMissingError); }],
+  dlopen__deps: [function() { error(dlopenMissingError); }],
+  _emscripten_dlopen__deps: [function() { error(dlopenMissingError); }],
+  __dlsym__deps: [function() { error(dlopenMissingError); }],
 #else
   $dlopenMissingError: `= ${dlopenMissingError}`,
   _dlopen_js__deps: ['$dlopenMissingError'],
   _emscripten_dlopen_js__deps: ['$dlopenMissingError'],
   _dlsym_js__deps: ['$dlopenMissingError'],
   _dlsym_catchup_js__deps: ['$dlopenMissingError'],
+  dlopen__deps: ['$dlopenMissingError'],
+  _emscripten_dlopen__deps: ['$dlopenMissingError'],
+  __dlsym__deps: ['$dlopenMissingError'],
 #endif
   _dlopen_js: function(handle) {
     abort(dlopenMissingError);
@@ -259,6 +265,16 @@ var LibraryDylink = {
   _dlsym_catchup_js: function(handle, symbolIndex) {
     abort(dlopenMissingError);
   },
+  dlopen: function(handle) {
+    abort(dlopenMissingError);
+  },
+  _emscripten_dlopen: function(handle, onsuccess, onerror, user_data) {
+    abort(dlopenMissingError);
+  },
+  __dlsym: function(handle, symbol) {
+    abort(dlopenMissingError);
+  },
+  _dlinit: function(main_dso_handle) {},
   _dlinit: function(main_dso_handle) {},
 #else // MAIN_MODULE != 0
   // dynamic linker/loader (a-la ld.so on ELF systems)

tools/system_libs.py

@@ -1127,7 +1127,6 @@ def get_files(self):
     libc_files += files_in_path(
         path='system/lib/libc',
         filenames=[
-          'dynlink.c',
           'emscripten_console.c',
           'emscripten_fiber.c',
           'emscripten_get_heap_size.c',
@@ -1145,6 +1144,9 @@ def get_files(self):
           'wasi-helpers.c',
         ])
 
+    if settings.RELOCATABLE:
+      libc_files += files_in_path(path='system/lib/libc', filenames=['dynlink.c'])
+
     libc_files += files_in_path(
         path='system/lib/pthread',
         filenames=['emscripten_atomic.c', 'thread_profiler.c'])