fix: 弱声明不能有内部链接

初始化数组的四个符号放在匿名 namespace 里了 —— clang 直接拒绝:
weak declaration cannot have internal linkage。移到外面。

Author: speak-agent

src/start.cpp

@@ -45,15 +45,19 @@ int main(int, char**, char**);
 
 }
 
-namespace {
-
 using initialiser = void (*)(int, char**, char**);
 
+// ⚠️ NOT in an anonymous namespace, and that is the compiler's rule rather than
+// a preference: internal linkage and a weak declaration are contradictory, and
+// clang says so in as many words. The linker script defines these, and a
+// program built without one gets the null range the weak declaration is for.
 [[gnu::weak]] extern initialiser __preinit_array_start[];
 [[gnu::weak]] extern initialiser __preinit_array_end[];
 [[gnu::weak]] extern initialiser __init_array_start[];
 [[gnu::weak]] extern initialiser __init_array_end[];
 
+namespace {
+
 void run_initialisers() {
     // ⚠️ Only when no C library took the hand-over. One that did runs these
     // itself, and running them twice constructs every static object twice.