bug#42702: catch2 build failure on ARM

[maxim . cournoyer]

maxim.cournoyer@gmail.com writes:

> On ARM systems, (armhf-linux, aarch64-linux), the catch2 package fails to 
> build, due to a
> compilation warning treated as an error:
>
> [ 90%] Building CXX object 
> CMakeFiles/SelfTest.dir/include/reporters/catch_reporter_xml.cpp.o
> /gnu/store/ap7hgyv4rjqmhg4a6cb6cypsh3g1f5q4-gcc-7.5.0/bin/c++   
> -I/tmp/guix-build-catch2-2.1.2.drv-0/source/include  -O2 -g -DNDEBUG   -Wall 
> -Wextra -Wunreachable-code -Wpedantic -Werror -std=c++11 -o 
> CMakeFiles/SelfTest.dir/include/reporters/catch_reporter_xml.cpp.o -c 
> /tmp/guix-build-catch2-2.1.2.drv-0/source/include/reporters/catch_reporter_xml.cpp
> /tmp/guix-build-catch2-2.1.2.drv-0/source/include/internal/catch_tostring.cpp:
>  In static member function ‘static std::__cxx11::string 
> Catch::StringMaker<char>::convert(char)’:
> /tmp/guix-build-catch2-2.1.2.drv-0/source/include/internal/catch_tostring.cpp:202:21:
>  error: comparison is always true due to limited range of data type 
> [-Werror=type-limits]
>      } else if ('\0' <= value && value < ' ') {
>                 ~~~~~^~~~~~~~

This is also the case for i686-linux.