Revert "Allow proto_library()'s proto_out_dir to be a source-root-absolute path"

This reverts commit 6a2e4d995d70a670b11c65f4e23fc17705b55ed2.

Reason for revert: Deterministic Linux bot is failing; this is our best guess. We believe this doesn't do the right thing for incremental builds.

See bug 950052.

Original change's description:
> Allow proto_library()'s proto_out_dir to be a source-root-absolute path
> 
> Also:
>  * Adds a disabled-behind-gn-arg check for targets that generate
>    .pb.cc files outside of their target_gen_dir.
>    This is the main motivation for the change
>  * Adds a public_include_dirs template arg to serve the use-case
>    some targets have of wanting their #include paths to look
>    differently.
> 
> I hope to change the disabled check into an assert once I fix & roll
> subrepos.
> 
> Bug: 944928
> Change-Id: Ib8157b7a5cb653fafaf751661bf979fe4b3c6152
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1535535
> Reviewed-by: Nico Weber <[email protected]>
> Reviewed-by: Jonathan Metzman <[email protected]>
> Auto-Submit: Andrew Grieve <[email protected]>
> Commit-Queue: Andrew Grieve <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#648186}

[email protected],[email protected],[email protected]

Change-Id: I960fd7e87b04953f4b75e58dde346699f71925db
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 944928, 950052
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1555046
Reviewed-by: Avi Drissman <[email protected]>
Commit-Queue: Avi Drissman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#648302}
diff --git a/testing/libfuzzer/fuzzers/javascript_parser_proto_fuzzer.cc b/testing/libfuzzer/fuzzers/javascript_parser_proto_fuzzer.cc
index 56f39a0..e38f88e 100644
--- a/testing/libfuzzer/fuzzers/javascript_parser_proto_fuzzer.cc
+++ b/testing/libfuzzer/fuzzers/javascript_parser_proto_fuzzer.cc
@@ -6,7 +6,7 @@
 
 #include <iostream>
 
-#include "testing/libfuzzer/fuzzers/javascript_parser.pb.h"  // from out/gen
+#include "javascript_parser.pb.h"  // from out/gen
 #include "testing/libfuzzer/fuzzers/javascript_parser_proto_to_string.h"
 #include "third_party/libprotobuf-mutator/src/src/libfuzzer/libfuzzer_macro.h"