Lerc::GetLercInfo(): fix integer overflow
Lerc::GetLercInfo(): fix integer overflow

If Lerc2::GetHeaderInfo() on a band > 1 returns a huge blob size,
we can overflow the total header blob size while adding it to the
existing size, leading to a negative value and later overflows.

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=11016
Credit to OSS-Fuzz

Esri/lerc,Esri/lerc,Esri/lerc,Esri/lerc,Esri/lerc,Esri/lerc,Esri/lerc