Add a new option to the linker: --error-handling-script=<NAME>. Run the script <NAME> if an undefined symbol or unfound library error is encountered.

PR 26626
	* ldmain.c (undefined_symbol): If an error handlign script is
	available, call it.
	* ldfile.c  (error_handling_script): Declare.
	(ldfile_open_file): If a library cannot be found and an error
	handling script is available, call it.
	* ldmain.h  (error_handling_script): Prototype.
	* ldlex.h (OPTION_ERROR_HANDLING_SCRIPT): Define.
	* lexsup.c (ld_options): Add --error-handling-script.
	(parse_args): Add support for --errror-handling-script.
	* ld.texi: Document the new feature.
	* configure.ac: Add --error-handling-script option to disable
	support for the new feature.
	* NEWS: Mention the new feature.
	* config.in: Regenerate.
	* configure: Regenerate.

ld/configure

@@ -835,6 +835,7 @@ enable_new_dtags
 enable_relro
 enable_textrel_check
 enable_separate_code
+enable_error_handling_script
 enable_default_hash_style
 enable_libctf
 enable_werror
@@ -1505,6 +1506,9 @@ Optional Features:
   --enable-textrel-check=[yes|no|warning|error]
                           enable DT_TEXTREL check in ELF linker
   --enable-separate-code  enable -z separate-code in ELF linker by default
+  --enable-error-handling-script
+                          enable/disable support for the
+                          --error-handling-script option
   --enable-default-hash-style={sysv,gnu,both}
                           use this default hash style
   --enable-libctf         Handle .ctf type-info sections [default=yes]
@@ -12039,7 +12043,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12042 "configure"
+#line 12046 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12145,7 +12149,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12148 "configure"
+#line 12152 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -15945,6 +15949,17 @@ esac
 fi
 
 
+# Decide if --error-handling-script should be supported.
+ac_support_error_handling_script=unset
+# Check whether --enable-error-handling-script was given.
+if test "${enable_error_handling_script+set}" = set; then :
+  enableval=$enable_error_handling_script; case "${enableval}" in
+  yes) ac_support_error_handling_script=1 ;;
+  no)  ac_support_error_handling_script=0 ;;
+esac
+fi
+
+
 # Decide which "--hash-style" to use by default
 # Provide a configure time option to override our default.
 # Check whether --enable-default-hash-style was given.
@@ -17739,6 +17754,15 @@ cat >>confdefs.h <<_ACEOF
 _ACEOF
 
 
+if test "${ac_support_error_handling_script}" = unset; then
+  ac_support_error_handling_script=1
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define SUPPORT_ERROR_HANDLING_SCRIPT $ac_support_error_handling_script
+_ACEOF
+
+
 
 cat >>confdefs.h <<_ACEOF
 #define DEFAULT_EMIT_SYSV_HASH $ac_default_emit_sysv_hash