linker: ensure global constructors only run once

Rename the symbols used to denote the locations of the global
constructor lists and modify the Zephyr start-up code accordingly.
On POSIX systems this ensures that the native libc init code won't
find any constructors to run before Zephyr loads.

Fixes #39347, #36858

Signed-off-by: David Palchak <palchak@google.com>

kernel/init.c

diff --git a/kernel/init.c b/kernel/init.c
index d4acea3..f6093ab 100644
--- a/kernel/init.c
+++ b/kernel/init.c
@@ -216,7 +216,7 @@
 #endif
 	boot_banner();
 
-#if defined(CONFIG_CPLUSPLUS) && !defined(CONFIG_ARCH_POSIX)
+#if defined(CONFIG_CPLUSPLUS)
 	void z_cpp_init_static(void);
 	z_cpp_init_static();
 #endif