StaticTlsLayout: add exe/tcb and solib layout

Replace reserve_tcb with reserve_exe_segment_and_tcb, which lays out both
the TCB and the executable's TLS segment, accounting for the difference in
layout between variant 1 and variant 2 targets.

The function isn't actually called with a non-null TlsSegment* yet.

Bug: http://b/78026329
Test: bionic unit tests
Change-Id: Ibd6238577423a7d0451f36da7e64912046959796
diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index 68650ed..6ba6583 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -86,7 +86,7 @@
 static void layout_static_tls() {
   StaticTlsLayout& layout = __libc_shared_globals()->static_tls_layout;
   layout.reserve_bionic_tls();
-  layout.reserve_tcb();
+  layout.reserve_exe_segment_and_tcb(nullptr);
   layout.finish_layout();
 }