[gdb/testsuite] Fix gdb.base/skip-solib.exp for remote target

Fix test-case gdb.base/skip-solib.exp for target board
remote-gdbserver-on-localhost using gdb_load_shlib.

Tested on x86_64-linux.
diff --git a/gdb/testsuite/gdb.base/skip-solib.exp b/gdb/testsuite/gdb.base/skip-solib.exp
index f01196c..9caf7e0 100644
--- a/gdb/testsuite/gdb.base/skip-solib.exp
+++ b/gdb/testsuite/gdb.base/skip-solib.exp
@@ -61,6 +61,7 @@
 with_test_prefix "ignoring solib file" {
 
     clean_restart ${executable_main}
+    gdb_load_shlib $binfile_lib
 
     gdb_test "skip file ${srcfile_lib}" \
 	"File ${srcfile_lib} will be skipped when stepping." \
@@ -87,6 +88,7 @@
 #
 with_test_prefix "ignoring solib function" {
     clean_restart ${executable_main}
+    gdb_load_shlib $binfile_lib
 
     gdb_test "skip function multiply" \
 	"Function multiply will be skipped when stepping\\." \