Use dynamic libusb on Linux

[rhn]

Fedora uses libusbx, and doesn't come with a statically linked version.

Here's what the devel package has:

# rpm -ql libusbx-devel
/usr/include/libusb-1.0
/usr/include/libusb-1.0/libusb.h
/usr/lib64/libusb-1.0.so
/usr/lib64/pkgconfig/libusb-1.0.pc

pic32prog is not in Fedora at the moment, and while I don't know the reason, this is one roadblock.

I'm not sure that the library needs to be statically linked, so I hope this doesn't break anything.

[rhn]

I've noticed that a better change was applied:

#45

and then reverted already:

#50

Without this change, pic32prog will never be buildable or packageble in some modern Linux distributions. I was under the impression that the pkg-config check preserved static buildability when available, and dynamic linking in packages is not the original author's problem anyway.

What's an acceptable way to solve this problem?