energy_uj errors in log even when iGPU optimization disabled

[kroq-gar78]

Describe the bug Per #337, gamemoded produces errors when reading /sys/class/powercap/intel-rapl*/*/energy_uj because it is usually run as an unprivileged user. Disabling iGPU optimization with igpu_power_threshold=-1 does not get rid of this error. Even though it is a non-fatal error, this log message can mislead users when debugging possible GameMode issues.

To Reproduce Steps used to reproduce the behavior:

1. Run gamemoded
2. Run gamemode-simulate-game in a separate terminal
3. Output of gamemoded:

   Entering Game Mode...
   governor was initially set to [performance]
   Requesting update of governor policy to performance
   ERROR: Configured iGPU power threshold value '-1.000000' is invalid, ignoring iGPU default governor.
   ERROR: Failed to open file for read /sys/class/powercap/intel-rapl/intel-rapl:0/intel-rapl:0:0/energy_uj

Expected behavior GameMode should not attempt to read energy_uj if iGPU optimization is disabled.

System Info (please complete the following information):

• OS and version: Manjaro Linux, kernel 5.17.13
• GameMode Version: v1.6.1

Additional context It looks like these 2 lines contain the only instances of calls to get_*energy_uj:

• https://github.com/FeralInteractive/gamemode/blob/126e67fb6b60051c2a9095856c120aab9e2ccb17/daemon/gamemode-context.c#L262
• https://github.com/FeralInteractive/gamemode/blob/126e67fb6b60051c2a9095856c120aab9e2ccb17/daemon/gamemode-context.c#L288

[eternal-sorrow]

Configured iGPU power threshold value '-1.000000' is invalid, ignoring iGPU default governor.

This doesn't seem right.