If we want to build other projects (kiwix-lib, kiwix-tools) with travis,
it is better to have all dependencies already compiled.
kiwix-build project now compiles them and publishes the dependencies
archive at the right place where other projects can use them.
The dependencies of libzim were missing.
If we run a single run to compile everything everything run correctly
as zlib and lzma will be installed because of kiwix-lib (and other)
dependencies.
By limiting the choices in the argument parser, we catch argument error
at parsing and we can provide useful output (the names of dependencies
we can handle) to user in the help or in the error message.
The OpenZim source contains the zimlib source but also the zimwriterfs
source.
There is no zimwriterfs dependency for now but it is better to separate
source from the dependency for latter commit.
There is a bug in 56_1 version when compiling resource.
This is fixed in 58_2.
However the last version 58_2 use _create_local and _free_locale symbols on
Windows and we need to add the right libs to the compilation command.
AC_SEARCH_LIBS try to compile and use a symbol (timer_create) using
a lib (rt).
But, in fact, it also try to use the symbol but without using the lib.
If it's work, it consider that the libs is found and set the ac_res
variable to "none required".
So, we must check the value of ac_res to know if we must add '-lrt' to
the pkg-config file.
On recent version of the NDK (r13b), `exec_elf.h` has been removed for
API level >= 20. On 64 bits, we need the API level 21, and then,
a defined (ELF64_ST_INFO) is missing.
We readd it where (and if) we need it.
'properties' is too close of the meson definition and we need to duplicate
the entries for 'c_link_args' and 'cpp_link_args'.
By using 'extra_libs' we have a more functional definition of what we want.
If ccache is availble, use it. It can improve a lot the compilation time.
We do not change the meson_cross_file.txt as, for now, meson doesn't
support ccache when cross-compiling.
