[K/N] Add own gettid implementation

Call-checker can't handle syscalls yet, so instead we wrap it
inside function.

kotlin-native/runtime/src/main/cpp/Porting.cpp

@@ -258,6 +258,13 @@ void onThreadExit(void (*destructor)(void*), void* destructorParameter) {
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/syscall.h>
+
+/**
+ * We can't use gettid from glibc 2.30 because it is too new for us.
+ */
+NO_EXTERNAL_CALLS_CHECK NO_INLINE int gettid() {
+    return static_cast<int>(syscall(__NR_gettid));
+}
 #endif
 
 NO_EXTERNAL_CALLS_CHECK int currentThreadId() {
@@ -278,7 +285,7 @@ NO_EXTERNAL_CALLS_CHECK int currentThreadId() {
 #elif KONAN_ANDROID
     return gettid();
 #elif KONAN_LINUX
-    return syscall(__NR_gettid);
+    return gettid();
 #elif KONAN_WINDOWS
   return GetCurrentThreadId();
 #else

kotlin-native/runtime/src/mm/cpp/CallsChecker.cpp

@@ -146,6 +146,8 @@ extern "C" const char* Kotlin_callsCheckerGoodFunctionNames[] = {
         "vsnprintf",
         "bcmp",
 
+        "gettid",
+
         "getenv",
         "setenv",
         "unsetenv",