Support space in paths of data-dependencies.

The runfiles manifest remains the same for files
without space in their runfiles-relative path.

For files with space in their runfiles-relative
path: the delimiter between runfile path and link
target is now '|' instead of space. Tools and
rules that consume runfiles manifests should test
for a '|' delimiter, and if missing, fall back to
space.

This design ensures that manifest consumers keep
working without having to handle '|', as long as
all data-dependencies are space-free. Otherwise
they break, but they would break today anyway.

Fixes bazelbuild#4327

Change-Id: I37ce3b3ef2a9e92691e987588b0e6d67969a78c5

Change-Id: I1072b65ee546d37dfe969c73c76980e43234a3fe

Change-Id: I611454ea7d6001b97d6f3417b7331c978070fc3f

Change-Id: I636118c40f2c1ef6e2792e1d0ceb07aff9e30880