A CMake option LARGE_FILE_SUPPORT is created if and only if
-D_FILE_OFFSET_BITS=64 affects sizeof(off_t).
This is needed on many 32-bit platforms and even with 64-bit builds
with MinGW-w64 to get support for files larger than 2 GiB.
(cherry picked from commit 36fabdbe67)
The syntax "if(DEFINED CACHE{FOO})" requires CMake 3.14.
In some other places the code treats the cache variables
like normal variables already (${FOO} or if(FOO) is used,
not ${CACHE{FOO}).
Thanks to ygrek for reporting the bug on IRC.
This version matches CMake files in the master branch (commit
265daa873c) except that this omits
two source files that aren't in v5.2 and in the beginning of
CMakeLists.txt the first paragraph in the comment is slightly
different to point out possible issues in building shared liblzma.
Lasse Collin