[PATCH] fix system-abseil build even with 2022 version

[PATCH] fix system-abseil build even with 2022 version

actually it seems it was a internal abseil header from pdfium vs. system
header mismatch. Include proper absl/container/inlined_vector.h if using
system-abseil.

While at it we can also just use pkg-config, no idea why I did it
without back then. Also gets the advantage that it knows that the libs
needed for absl_inlined_vector is actually
-labsl_throw_delegate -labsl_raw_logging_internal -labsl_log_severity

This effectively reverts e89723103313ec4366ee58144c47d7a5c16bf838

Change-Id: Ide4f79860b4e0673c5c6587d503058bdd2930744

Gbp-Pq: Name fix-system-abseil-build.diff