Bump NDK to r26 (#8213)

Changes: https://github.com/android/ndk/wiki/Changelog-r26#announcements

NDK r26 has the following changes which are interesting to us:

  * libc++ has been updated. The NDK's libc++ now comes directly from
    our LLVM toolchain, so every future LLVM update is also a libc++
    update.
  * Updated LLVM to clang-r487747c, based on LLVM 17 development

The `libc++` update brings internal implementation changes, and as a
result we no longer need to partially instantiate a couple of classes
previously underlying the `vector<T>` and `basic_string<T>`
implementations.

build-tools/xaprepare/xaprepare/ConfigAndData/BuildAndroidPlatforms.cs

@@ -5,10 +5,10 @@ namespace Xamarin.Android.Prepare
 {
 	class BuildAndroidPlatforms
 	{
-		public const string AndroidNdkVersion = "25c";
-		public const string AndroidNdkPkgRevision = "25.2.9519653";
+		public const string AndroidNdkVersion = "26";
+		public const string AndroidNdkPkgRevision = "26.0.10792818";
 		public const int NdkMinimumAPI = 21;
-		public const int NdkMinimumAPILegacy32 = 19;
+		public const int NdkMinimumAPILegacy32 = 21;
 
 		public static readonly List<AndroidPlatform> AllPlatforms = new List<AndroidPlatform> {
 			new AndroidPlatform (apiName: "",                       apiLevel: 1,  platformID: "1"),

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Tasks/NdkUtilTests.cs

@@ -41,7 +41,7 @@ public void TestNdkUtil ()
 				Assert.IsTrue (ndk.ValidateNdkPlatform (arch, enableLLVM: false));
 				Assert.AreEqual (0, errors.Count, "NdkTools.ValidateNdkPlatform should not have returned false.");
 				int level = ndk.GetMinimumApiLevelFor (arch);
-				int expected = 19;
+				int expected = 21;
 				Assert.AreEqual (expected, level, $"Min Api Level for {arch} should be {expected}.");
 				var compilerNoQuotes = ndk.GetToolPath (NdkToolKind.CompilerC, arch, level);
 				Assert.AreEqual (0, errors.Count, "NdkTools.GetToolPath should not have errored.");

src/monodroid/CMakeLists.txt

@@ -505,7 +505,6 @@ if(ANDROID)
       ${BIONIC_SOURCES_DIR}/cxa_guard.cc
       ${SOURCES_DIR}/cxx-abi/string.cc
       ${SOURCES_DIR}/cxx-abi/terminate.cc
-      ${SOURCES_DIR}/cxx-abi/vector.cc
       )
   endif()
 else()

src/monodroid/jni/cxx-abi/string.cc

@@ -7,7 +7,6 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template class __attribute__ ((__visibility__("hidden"))) __basic_string_common<true>;
 template class __attribute__ ((__visibility__("hidden"))) basic_string<char>;
 
 _LIBCPP_END_NAMESPACE_STD

tests/Mono.Android-Tests/jni/reuse-threads.c

@@ -75,6 +75,7 @@
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 #include <pthread.h>
 #include <semaphore.h>
@@ -206,15 +207,17 @@ rt_invoke_callback_on_new_thread (CB cb)
 	return 0;
 }
 
+static int _register_retval = 0;
+
 /* We return -2 for errors, because -1 is reserved for the pthreads PTHREAD_CANCELED special value, indicating that the
  * thread was canceled. */
-static int
+static void*
 _register_type_from_new_thread (void *data)
 {
 	RegisterFromThreadContext *context = (RegisterFromThreadContext*)data;
 
 	if (context == NULL) {
-		return -100;
+		return (void*)(intptr_t)-100;
 	}
 
 	JNIEnv *env = _get_env ("_register_type_from_new_thread");
@@ -227,7 +230,7 @@ _register_type_from_new_thread (void *data)
 			(*env)->ExceptionClear (env);
 		}
 
-		return -101;
+		return (void*)(intptr_t)-101;
 	}
 
 	int ret = 0;
@@ -286,7 +289,7 @@ _register_type_from_new_thread (void *data)
   cleanup:
 	(*env)->PopLocalFrame (env, NULL);
 
-	return ret;
+	return (void*)(intptr_t)ret;
 }
 
 JNIEXPORT int JNICALL
@@ -312,10 +315,10 @@ rt_register_type_on_new_thread (const char *java_type_name, jobject class_loader
 		return -201;
 	}
 
-	if ((int)tr == -1 /* PTHREAD_CANCELED - not defined in bionic */) {
+	if ((int)(intptr_t)tr == -1 /* PTHREAD_CANCELED - not defined in bionic */) {
 		__android_log_print (ANDROID_LOG_INFO, "XA/RuntimeTest", "RegisterOnNewThread: worker thread was canceled");
 		return -202;
 	}
 
-	return (int)tr;
+	return (int)(intptr_t)tr;
 }