AWS's SDK by default tries to prepend its install root to each of the
library paths; this obviously fails with the absolute paths that Nix
gives it. Worse, it computes the installation root by walking up the
filesystem from its cmake file, so even if the AWSSDK_ROOT_DIR is
explicitly set to the root directory, it gets replaced with the path
to the derivation's dev output.

This is all fixed with a patch to the cmake files that generate the
installed configuration.

Once this is fixed, it *still* doesn't work because the export
generator built into cmake insists on adding `$out/include` to the
header search path; when importing this configuration in another
package, cmake will fail because `$out/include` doesn't exist (After
all, it was relocated by a fixup hook). A small postFixupHook will
recreate the directory and make cmake happy.

(cherry picked from commit 9d78852)

Boost generates its installed cmake configuration using custom logic
in its own build system; while this logic *knows* where it should be
installed, the generated config overrides the correct information with
new paths based on the location of the cmake configuration file in an
attempt to let the package be relocated after installation.

This patch simply undoes that.

(cherry picked from commit 777df0b)