Fix error message being cut off.

The current char msg is not large enough for the error message.
Change to a std::string to avoid this problem completely.

Test: Ran atest FrameworksServicesTests on oriole_hwasan-userdebug
Test: verifying entire error message present.
Change-Id: I663bcbafd96572151395a9054b09764dc8e05b51
1 file changed