Fix mistake when setting linker flags

[illwieckz]

There was a stupid mistake inverting between executable-linker-flags and everythng-linker-flags.

Fixes #1573:

• Still getting argument unused during compilation: '-pie' with dll #1573

I verified that even after fixing this maCOS still complains about -pie not being used on executables so I kept the macOS test to disable -pie:

[100%] Linking CXX executable daemonded
clang++: warning: argument unused during compilation: '-pie' [-Wunused-command-line-argument]

[illwieckz]

I also noticed that -pie reruires -fPIC, so since -fPIC is optional, this now tests for this flag being supported before testing for -pie. This is probably useless and this may skip a flag test if -fPIC isn't supported, this should be very rare but this is more consistent when written this way.

$ clang -pie a.cpp && echo done
ld: error: relocation R_X86_64_64 cannot be used against local symbol; recompile with -fPIC
>>> defined in /tmp/a-b05268.o
>>> referenced by a.cpp
>>>               /tmp/a-b05268.o:(main)
clang: error: linker command failed with exit code 1 (use -v to see invocation)

$ clang -fPIC -pie a.cpp && echo done
done

This also fixes an harmless typo.

[illwieckz]

Thanks for the review!