Bump GLib min req to 2.34

UPower uses g_clear_pointer several places in the code, but is
available starting in 2.34. Update UPowers minimum version to
match.
https://bugs.freedesktop.org/show_bug.cgi?id=83850

Signed-off-by: Richard Hughes <richard@hughsie.com>
Fencepost array access error

Array 'temp_data[100]' accessed at index 100, which is out of
bounds.
https://bugs.freedesktop.org/show_bug.cgi?id=71066

Signed-off-by: Richard Hughes <richard@hughsie.com>
Correct check to prevent the display of invalid ASCII codes

Cppcheck found it as a logical conjunction always evaluates to
false: EXPR < 32 && EXPR > 126. Change the expression to an Or.
https://bugs.freedesktop.org/show_bug.cgi?id=71066

Signed-off-by: Richard Hughes <richard@hughsie.com>