on_dso_load_select: run after on_dso_load_ctx

Add priorities to ensure on_dso_load_select runs after on_dso_load_ctx.
Otherwise osmo_ctx->global (used via define OTC_GLOBAL) points to NULL
and causes a segfault in osmo_fd_lookup_table_extend.

Use numbers 101 and 102, as "0 to 100 are reserved for the
implementation" and cause an error from GCC.

Fixes: OS#5946
Fixes: c46a15d8 ("select: Optimize osmo_fd_get_by_fd")
Change-Id: Ia2518e82530b93c535f8f5105513e21559b895ba
---
M src/core/context.c
M src/core/select.c
2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/core/context.c b/src/core/context.c
index 6b58565..a0b3a55 100644
--- a/src/core/context.c
+++ b/src/core/context.c
@@ -39,7 +39,7 @@
 }
 
 /* initialize osmo_ctx on main tread */
-static __attribute__((constructor)) void on_dso_load_ctx(void)
+static __attribute__((constructor(101))) void on_dso_load_ctx(void)
 {
 	OSMO_ASSERT(osmo_ctx_init("main") == 0);
 }
diff --git a/src/core/select.c b/src/core/select.c
index c60cd8e..69fa763 100644
--- a/src/core/select.c
+++ b/src/core/select.c
@@ -534,8 +534,9 @@
 	osmo_fd_lookup_table_extend(0);
 }
 
-/* ensure main thread always has pre-initialized osmo_fds */
-static __attribute__((constructor)) void on_dso_load_select(void)
+/* ensure main thread always has pre-initialized osmo_fds
+ * priority 102: must run after on_dso_load_ctx */
+static __attribute__((constructor(102))) void on_dso_load_select(void)
 {
 	osmo_select_init();
 }

