Often other Libs flags have semantics that are based on their context
with -l arguments. For example, the GNU linker options
-Bdynamic/-Bstatic pertain only to the objects or link options that
follow them. So, a valid link command containing these options would get
mangled by pkg-config since it separates -l flags from others..
-Bdynamic -la -Bstatic -lb -> -Bdynamic -Bstatic -la -lb
Instead, output -l and other Libs flags in a single pass so they mantain
their ordering.
Freedesktop #19950 (https://bugs.freedesktop.org/show_bug.cgi?id=19950)
Outputting other Libs flags such as -Wl,foo just prior to the -l Libs
flags gives a better chance the --libs output will be correct. This
should be no change in the usage of the output since pkg-config
currently groups all flag types together.
For some flags, pkg-config will sort them by the depth of their .pc path
before outputting. The idea is that flags from a deeper path should come
earlier in the command line. This makes sense for -L and -I flags, but
not for generic linker and compiler flags. For these flags and -l flags,
it makes sense to sort them only by package order.
The current tests are good at checking whether gathering the Cflags or
Libs from one or two packages works correctly, but they don't check the
sorting algorithm much at all. In particular, the interactions between
the package order in the Requires chain and in the path can make the
sorting of the flags subtly different.
