tools build: Fix a number of Wconversion warnings

tools build: Fix a number of Wconversion warnings

There's some expressed interest in having the compiler flag
-Wconversion detect at build time certain kinds of potential problems:
https://lore.kernel.org/lkml/20250103182532.GB781381@e132581.arm.com/

As feature detection passes -Wconversion from CFLAGS when set, the
feature detection compile tests need to not fail because of
-Wconversion as the failure will be interpretted as a missing
feature. Switch various types to avoid the -Wconversion issue, the
exact meaning of the code is unimportant as it is typically looking
for header file definitions.

Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250106215443.198633-1-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>