Add support for disabled exceptions

[jeremiahar]

This fixes a build error when compiled with -fno-exceptions:

/usr/include/boost/stacktrace/stacktrace.hpp:98:11: error: exception handling disabled, use ‘-fexceptions’ to enable
98 | } catch (...) {

[coveralls]

Coverage remained the same at 92.291% when pulling a8a4cef on jeremiahar:develop into f931528 on boostorg:develop.

[apolukhin]

Many thanks for the PR!