perf util: Fix compression checks returning -1 as bool

The lzma_is_compressed and gzip_is_compressed functions are declared
to return a "bool" type, but in case of an error (e.g., file open
failure), they incorrectly returned -1.

A bool type is a boolean value that is either true or false.
Returning -1 for a bool return type can lead to unexpected behavior
and may violate strict type-checking in some compilers.

Fix the return value to be false in error cases, ensuring the function
adheres to its declared return type improves for preventing potential
bugs related to type mismatch.

Fixes: 4b57fd44 ("perf tools: Add lzma_is_compressed function")
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Yunseong Kim <ysk@kzalloc.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Link: https://lore.kernel.org/r/20250822162506.316844-3-ysk@kzalloc.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>