[Ada] Fix libgnat.so link failure on systems with older glibc

[Eric Botcazou]

It's a regression present on all active branches for older glibc versions, 
where dladdr is still in the libdl.so library, and not included in libc.so as 
in newer glibc versions.

Applied on all active branches.


2026-03-14  Matthias Klose  <d...@gcc.gnu.org>

        PR ada/107475
        * Makefile.rtl (s390% linux%): Define MISCLIB.
        (arm% linux-gnueabi%): Likewise.
        (%x32 linux%): Likewise.

-- 
Eric Botcazou
diff --git a/gcc/ada/Makefile.rtl b/gcc/ada/Makefile.rtl
index eed13703f94..fbb0a0b2eec 100644
--- a/gcc/ada/Makefile.rtl
+++ b/gcc/ada/Makefile.rtl
@@ -2036,6 +2036,7 @@ ifeq ($(strip $(filter-out s390% linux%,$(target_cpu) $(target_os))),)
   EXTRA_GNATRTL_TASKING_OBJS=s-linux.o
   EH_MECHANISM=-gcc
   THREADSLIB = -lpthread
+  MISCLIB = -ldl
   GNATLIB_SHARED = gnatlib-shared-dual
   LIBRARY_VERSION := $(LIB_VERSION)
 endif
@@ -2529,6 +2530,7 @@ ifeq ($(strip $(filter-out arm% linux-gnueabi%,$(target_cpu) $(target_os))),)
   EXTRA_GNATRTL_TASKING_OBJS=s-linux.o
   EH_MECHANISM=-arm
   THREADSLIB = -lpthread
+  MISCLIB = -ldl
   GNATLIB_SHARED = gnatlib-shared-dual
   GMEM_LIB = gmemlib
   LIBRARY_VERSION := $(LIB_VERSION)
@@ -2968,6 +2970,7 @@ ifeq ($(strip $(filter-out %x32 linux%,$(target_cpu) $(target_os))),)
   EXTRA_GNATRTL_TASKING_OBJS=s-linux.o a-exetim.o
   EH_MECHANISM=-gcc
   THREADSLIB=-lpthread -lrt
+  MISCLIB = -ldl
   GNATLIB_SHARED=gnatlib-shared-dual
   GMEM_LIB = gmemlib
   LIBRARY_VERSION := $(LIB_VERSION)