Move dlerror out of a TLS slot and into a pthread_internal_t member.

Bug: N/A
Test: boots, tests pass.
Change-Id: Idf25d2ee457a5d26d0bdd6281cee72c345c8b755
diff --git a/libc/bionic/pthread_internal.h b/libc/bionic/pthread_internal.h
index 5a5318d..2ebd2b4 100644
--- a/libc/bionic/pthread_internal.h
+++ b/libc/bionic/pthread_internal.h
@@ -139,6 +139,7 @@
    * The dynamic linker implements dlerror(3), which makes it hard for us to implement this
    * per-thread buffer by simply using malloc(3) and free(3).
    */
+  char* current_dlerror;
 #define __BIONIC_DLERROR_BUFFER_SIZE 512
   char dlerror_buffer[__BIONIC_DLERROR_BUFFER_SIZE];