No test coverage of the alternative implementation with %f, %g, %e, %a

[eyalroz]

The alternative implementation flag ('#') can be used with the specifiers %f, %g, %e, %a, %o and %x (and their uppercase versions). However, test_suite.cpp only uses the flag with %o and %x (and %d, %b, %iand%u` if non-standard format strings are supported).