perf tools: Remove cast of non-variadic function to variadic

perf tools: Remove cast of non-variadic function to variadic

The 4fb71074a570 (perf ui/hist: Consolidate hpp helpers) cset introduced
a cast of percent_color_snprintf to a function pointer type with
varargs.  Change percent_color_snprintf to be variadic and remove the
cast.

The symptom of this was all percentages being reported as 0.00% in perf
report --stdio output on the armhf arch.

Signed-off-by: Michael Hudson-Doyle <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Acked-by: Will Deacon <[email protected]>
Cc: Jean Pihet <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>