Implemented support for thread-local storage

photon/libc/include/errno.h

@@ -3,13 +3,14 @@
 
 #include <sys/_errno.h>
 
-#define errno (*__errno_location())
+#define errno (__get_errno())
 
 #if defined(__cplusplus)
 extern "C" {
 #endif
 
-extern int *__errno_location(void);
+extern void __set_errno(int v);
+extern int __get_errno(void);
 
 #if defined(__cplusplus)
 }

photon/libc/sys/horizon/machine/x86_64/pthread.s

@@ -0,0 +1,11 @@
+.global pthread_self
+.type pthread_self, @function
+
+pthread_self:
+    push %rbp
+    mov %rsp, %rbp
+
+    mov %fs:0, %rax
+
+    pop %rbp
+    ret