Correctly detect if linker supports noexecstack

[ryandesign]

When testing for support of multiple flags, the flags must be separated by semicolons not spaces.

See https://gitlab.kitware.com/cmake/cmake/-/issues/26024

When referenced elsewhere, enclose the flag variable in quotation marks so that it is passed through unmodified.

@MarcusCalhoun-Lopez I believe this solution is preferable to the one proposed in #4056.