Bug#34025: mysql_config is not returning -ldl lib flag needed when using embedded server

mysql_config did not output -ldl (or equivalent) when needed for --libmysqld-libs,
so its output could be insufficient to build an application using the embedded
server.

LIBDL was already set in configure; it's now propagated all the way into the
relevant mysql_config scripts.

scripts/Makefile.am:
  We "manually" replace configure's constants in .sh scripts using sed,
  so AC_SUBST() alone is not good enough. Add LIBDL to the substitution
  list; we'll be needing it for mysql_config --libmysqld-libs
scripts/mysql_config.pl.in:
  Add LIBDL (usually -ldl) to output of mysql_config --libmysqld-libs (perl version)
scripts/mysql_config.sh:
  Add LIBDL (usually -ldl) to output of mysql_config --libmysqld-libs (shell version)

scripts/Makefile.am

@@ -162,6 +162,7 @@ SUFFIXES = .sh
 	  -e 's!@''CFLAGS''@!@CFLAGS@!'\
 	  -e 's!@''CXXFLAGS''@!@CXXFLAGS@!'\
 	  -e 's!@''LDFLAGS''@!@LDFLAGS@!'\
+	  -e 's!@''LIBDL''@!@LIBDL@!'\
 	  -e 's!@''CLIENT_LIBS''@!@CLIENT_LIBS@!' \
 	  -e 's!@''ZLIB_LIBS''@!@ZLIB_LIBS@!' \
 	  -e 's!@''LIBS''@!@LIBS@!' \

scripts/mysql_config.pl.in

@@ -202,7 +202,7 @@ $flags->{libs} =
 $flags->{libs_r} =
   [@ldflags,@lib_r_opts,'@ZLIB_DEPS@','@LIBS@','@openssl_libs@'];
 $flags->{embedded_libs} =
-  [@ldflags,@lib_e_opts,'@ZLIB_DEPS@','@LIBS@','@WRAPLIBS@','@innodb_system_libs@','@openssl_libs@'];
+  [@ldflags,@lib_e_opts,'@LIBDL@','@ZLIB_DEPS@','@LIBS@','@WRAPLIBS@','@innodb_system_libs@','@openssl_libs@'];
 
 $flags->{include} = ["-I$pkgincludedir"];
 $flags->{cflags}  = [@{$flags->{include}},split(" ",'@CFLAGS@')];

scripts/mysql_config.sh

@@ -107,7 +107,7 @@ fi
 libs=" $ldflags -L$pkglibdir -lmysqlclient @ZLIB_DEPS@ @NON_THREADED_LIBS@"
 libs="$libs @openssl_libs@ @STATIC_NSS_FLAGS@ "
 libs_r=" $ldflags -L$pkglibdir -lmysqlclient_r @ZLIB_DEPS@ @LIBS@ @openssl_libs@ "
-embedded_libs=" $ldflags -L$pkglibdir -lmysqld @ZLIB_DEPS@ @LIBS@ @WRAPLIBS@ @innodb_system_libs@ @openssl_libs@ "
+embedded_libs=" $ldflags -L$pkglibdir -lmysqld @LIBDL@ @ZLIB_DEPS@ @LIBS@ @WRAPLIBS@ @innodb_system_libs@ @openssl_libs@ "
 
 if [ -r "$pkglibdir/libmygcc.a" ]; then
   # When linking against the static library with a different version of GCC