Removed stub for Linux /sys/power processing.

Apparently /sys/power doesn't expose battery information at this time.

src/power/SDL_power.c

@@ -30,7 +30,6 @@ typedef SDL_bool
     (*SDL_GetPowerInfo_Impl) (SDL_PowerState * state, int *seconds,
                               int *percent);
 
-SDL_bool SDL_GetPowerInfo_Linux_sys_power(SDL_PowerState *, int *, int *);
 SDL_bool SDL_GetPowerInfo_Linux_proc_acpi(SDL_PowerState *, int *, int *);
 SDL_bool SDL_GetPowerInfo_Linux_proc_apm(SDL_PowerState *, int *, int *);
 SDL_bool SDL_GetPowerInfo_Windows(SDL_PowerState *, int *, int *);
@@ -57,7 +56,6 @@ SDL_GetPowerInfo_Hardwired(SDL_PowerState * state, int *seconds, int *percent)
 static SDL_GetPowerInfo_Impl implementations[] = {
 #ifndef SDL_POWER_DISABLED
 #ifdef SDL_POWER_LINUX          /* in order of preference. More than could work. */
-    SDL_GetPowerInfo_Linux_sys_power,
     SDL_GetPowerInfo_Linux_proc_acpi,
     SDL_GetPowerInfo_Linux_proc_apm,
 #endif

src/power/linux/SDL_syspower.c

@@ -34,14 +34,6 @@
 
 #include "SDL_power.h"
 
-SDL_bool
-SDL_GetPowerInfo_Linux_sys_power(SDL_PowerState * state,
-                                 int *seconds, int *percent)
-{
-    return SDL_FALSE;           /* !!! FIXME: write me. */
-}
-
-
 static const char *proc_acpi_path = "/proc/acpi/battery";
 
 static int open_acpi_file(const char *node, const char *key)