Merge pull request #1143 from lioncash/leaks

frontend: Fix some possible memory leaks in lakka, rgui, and rmenu
Merge pull request #1144 from lioncash/leaks

xmb: Fix a potential memleak
Merge pull request #1145 from lioncash/leaks

Fix possible memory leaks in hidpad_ps3_connect, hidpad_ps4_connect, and hidpad_wii_connect
(RGUI) Get rid of unused variable
Should fix load_no_content cores not being able to be loaded from
the history list
rgui: Fix potential memory leak