The default input file for perf report is not handled the same way as
perf record does it for its output file. This leads to unexpected
behavior of perf report, etc. E.g.:
# perf record -a -e cpu-cycles sleep 2 | perf report | cat
failed to open perf.data: No such file or directory (try 'perf record' first)
While perf record writes to a fifo, perf report expects perf.data to
be read. This patch changes this to accept fifos as input file.
Also fixes char const* -> const char* type declaration for filename
strings.
v2:
* Prevent potential null pointer access to input_name in
builtin-report.c. Needed due to removal of patch "perf report: Setup
browser if stdout is a pipe"
Signed-off-by: Robert Richter <robert.richter@amd.com>