Refactor some code

- Write tests for cthreads
- Fix bugs in pe2.com tool
- Fix ASAN issue with GetDosEnviron()
- Consolidate the cthread header files
- Some code size optimizations for MODE=
- Attempted to squash a tls linker warning
- Attempted to get futexes working on FreeBSD

libc/nexgen32e/threaded.h

@@ -8,19 +8,12 @@ extern int __threaded;
 extern bool __tls_enabled;
 extern unsigned __tls_index;
 
+char *__get_tls(void) libcesque nosideeffect;
 void *__initialize_tls(char[64]);
 void __install_tls(char[64]);
 
 #if defined(__GNUC__) && defined(__x86_64__) && !defined(__STRICT_ANSI__)
-/**
- * Returns address of thread information block.
- *
- * This function must not be called until TLS is initialized.
- *
- * @see __install_tls()
- * @see clone()
- */
-static noasan inline char *__get_tls(void) {
+static noasan inline char *__get_tls_inline(void) {
   char *tib, *lin = (char *)0x30;
   if (IsLinux() || IsFreebsd() || IsNetbsd() || IsOpenbsd()) {
     asm("mov\t%%fs:(%1),%0" : "=a"(tib) : "r"(lin) : "memory");