Allow inlining of Location constructor

[peterbarker]

Board                    AP_Periph  blimp  bootloader  copter  heli  iofirmware  plane  rover  sub
CubeOrange-periph-heavy  0                                                                     
CubeRedPrimary                      -128   *           -128    -120              -128   -120   -128
Durandal                            -112   *           -104    -96               -112   -112   -112
Hitec-Airspeed           *                                                                     
KakuteH7-bdshot                     -112   *           -120    -120              -112   -120   -120
MatekF405                           -136   *           -144    -144              -136   -144   -144
Pixhawk1-1M-bdshot                  -144               -144    -136              -144   -144   -136
f103-QiotekPeriph        *                                                                     
f303-Universal           -16                                                                   
iomcu                                                                *                         
revo-mini                           -136   *           -136    -144              -144   -144   -144
skyviper-journey                                       -136                                    
skyviper-v2450                                         -144                                    

... also remove pointless assignment from a stack-constructed location object