Snippets for apngasm 2.91 from FreeBSD 150amd64

Sourced from https://pkg-status.freebsd.org/beefy23/data/latest-per-pkg/apngasm/2.91/150amd64-default.log.

• 7z/WindowIn.h:72:7: warning: misleading indentation; statement is not part of the previous 'if' [-Wmisleading-indentation]
     72 |       aBack++;
        |       ^
  

• 7z/DeflateEncoder.cc:636:10: warning: variable 'aNowPos' set but not used [-Wunused-but-set-variable]
    636 |   UINT64 aNowPos = 0;
        |          ^
  

• 7z/LZMAEncoder.cc:771:10: warning: variable 'aMatchByte' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
    771 |       if(m_PeviousIsMatch)
        |          ^~~~~~~~~~~~~~~~