[java-interop] logging; don't require RTLD_LOCAL

Context: dotnet/android#5031
Context: https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=3998131&view=logs&j=db00894d-3ef4-5d97-073c-254fbd613a41&t=379a81d4-3138-5f28-ec7b-ce4074947b64

The xamarin-android integration PR is experiencing integration test
failures with the Android Designer:

	Renderer >> 4 [monodroid] Calling into managed runtime init
	Renderer (error) >>
	Renderer (error) >> Unhandled Exception:
	Renderer (error) >> System.EntryPointNotFoundException: java_interop_jnienv_get_java_vm assembly:<unknown assembly> type:<unknown type> member:(null)
	Renderer (error) >> at (wrapper managed-to-native) Java.Interop.NativeMethods.java_interop_jnienv_get_java_vm(intptr,intptr&)
	Renderer (error) >> at Java.Interop.JniEnvironment+References.GetJavaVM (System.IntPtr jnienv, System.IntPtr& vm) [0x00000] in <0f003a4904fd44d0a8cc6a63962ab40b>:0
	Renderer (error) >> at Java.Interop.JniEnvironmentInfo.set_EnvironmentPointer (System.IntPtr value) [0x00037] in <0f003a4904fd44d0a8cc6a63962ab40b>:0
	Renderer (error) >> at Java.Interop.JniEnvironmentInfo..ctor (System.IntPtr environmentPointer, Java.Interop.JniRuntime runtime) [0x00006] in <0f003a4904fd44d0a8cc6a63962ab40b>:0
	Renderer (error) >> at Java.Interop.JniRuntime..ctor (Java.Interop.JniRuntime+CreationOptions options) [0x0017b] in <0f003a4904fd44d0a8cc6a63962ab40b>:0
	Renderer (error) >> at Android.Runtime.AndroidRuntime..ctor (System.IntPtr jnienv, System.IntPtr vm, System.Boolean allocNewObjectSupported, System.IntPtr classLoader, System.IntPtr classLoader_loadClass, System.Boolean jniAddNativeMethodRegistrationAttributePresent) [0x00000] in /Users/builder/azdo/_work/4/s/xamarin-android/src/Mono.Android/Android.Runtime/AndroidRuntime.cs:25

The question is, *why*.

@jonpryor still isn't sure, but has a conjecture: among the changes
involved is a "forced" change to always use `RTLD_LAZY | RTLD_LOCAL`,
no matter what the calling code actually specified.

For test purposes, update `java_interop_load_library()` to "pass
through" the flags value on Unix, so that the calling code can
continue to use e.g. `RTLD_GLOBAL`, if desired.

Let's see if that fixes anything?

Additionally, add MOAR LOGGING MESSAGES to help see what's happening.

Author: jonpryor

src/java-interop/java-interop-dlfcn.cc

@@ -1,6 +1,7 @@
 #include "java-interop.h"
 #include "java-interop-dlfcn.h"
 #include "java-interop-util.h"
+#include "java-interop-logger.h"
 
 #ifdef WINDOWS
 #include <libloaderapi.h>
@@ -59,6 +60,7 @@ _free_error (char **error)
 static void
 _set_error (char **error, const char *message)
 {
+	log_warn (LOG_DEFAULT, "# jonp: _set_error: message=%s", message);
 	if (error == nullptr)
 		return;
 	*error = java_interop_strdup (message);
@@ -67,14 +69,25 @@ _set_error (char **error, const char *message)
 static void
 _set_error_to_last_error (char **error)
 {
+#if 1
+	char *m = _get_last_dlerror ();
+	log_warn (LOG_DEFAULT, "# jonp: _set_error_to_last_error: %s", m);
+	if (error != nullptr) {
+		*error = m;
+		return;
+	}
+	free (m);
+#else
 	if (error == nullptr)
 		return;
 	*error = _get_last_dlerror ();
+#endif
 }
 
 void*
 java_interop_load_library (const char *path, unsigned int flags, char **error)
 {
+	log_warn (LOG_DEFAULT, "# jonp: java_interop_load_library: path=`%s`", path);
 	_free_error (error);
 	if (path == nullptr) {
 		_set_error (error, "path=nullptr is not supported");
@@ -105,7 +118,7 @@ java_interop_load_library (const char *path, unsigned int flags, char **error)
 
 #else   // ndef WINDOWS
 
-	handle  = dlopen (path, RTLD_LAZY | RTLD_LOCAL);
+	handle  = dlopen (path, flags);
 
 #endif  // ndef WINDOWS
 
@@ -119,6 +132,7 @@ java_interop_load_library (const char *path, unsigned int flags, char **error)
 void*
 java_interop_get_symbol_address (void *library, const char *symbol, char **error)
 {
+	log_warn (LOG_DEFAULT, "# jonp: java_interop_get_symbol_address: library=%p symbol=%s", library, symbol);
 	_free_error (error);
 
 	if (library == nullptr) {
@@ -147,13 +161,15 @@ java_interop_get_symbol_address (void *library, const char *symbol, char **error
 	if (address == nullptr) {
 		_set_error_to_last_error (error);
 	}
+	log_warn (LOG_DEFAULT, "# jonp: java_interop_get_symbol_address: address=%p", address);
 
 	return address;
 }
 
 int
 java_interop_close_library (void* library, char **error)
 {
+	log_warn (LOG_DEFAULT, "# jonp: java_interop_close_library: library=%p", library);
 	_free_error (error);
 	if (library == nullptr) {
 		_set_error (error, "library=nullptr");