Added the TCC compiler to the external folder and the associated projects.

external/TCC/lib/alloca86-bt.S

@@ -0,0 +1,47 @@
+/* ---------------------------------------------- */
+/* alloca86-bt.S */
+
+.globl __bound_alloca
+
+__bound_alloca:
+    pop     %edx
+    pop     %eax
+    mov     %eax, %ecx
+    add     $3,%eax
+    and     $-4,%eax
+    jz      p6
+
+#ifdef TCC_TARGET_PE
+p4:
+    cmp     $4096,%eax
+    jbe     p5
+    test    %eax,-4096(%esp)
+    sub     $4096,%esp
+    sub     $4096,%eax
+    jmp p4
+
+p5:
+#endif
+
+    sub     %eax,%esp
+    mov     %esp,%eax
+
+    push    %edx
+    push    %eax
+    push    %ecx
+    push    %eax
+    call   __bound_new_region
+    add    $8, %esp
+    pop     %eax
+    pop     %edx
+
+p6:
+    push    %edx
+    push    %edx
+    ret
+
+/* mark stack as nonexecutable */
+#if defined __ELF__ && defined __linux__
+    .section    .note.GNU-stack,"",@progbits
+#endif
+/* ---------------------------------------------- */