Revert "Add documentation about Valgrind LLD workaround"

This reverts commit 63c5fa9cf2250dcd91dd88d8233c0d9d93b1d917.

Reason for revert: Workaround no longer needed.

Original change's description:
> Add documentation about Valgrind LLD workaround
> 
> BUG=chromium:830706
> 
> Change-Id: I72ea6373d898953c10e523399655f1f630941b09
> Reviewed-on: https://pdfium-review.googlesource.com/30110
> Commit-Queue: Ryan Harrison <rharrison@chromium.org>
> Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>

TBR=rharrison@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:830706
Change-Id: I0920f6756925d038536ece40a155afa0220dde4c
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/69032
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
diff --git a/README.md b/README.md
index a79e18d..739d014 100644
--- a/README.md
+++ b/README.md
@@ -223,13 +223,6 @@
 `third_party/pdfium` in Chromium's source code.
 This includes code coverage from PDFium's fuzzers.
 
-## Profiling
-
-Valgrind and other profiling tools do not work correctly with the standard build
-setup that PDFium uses. You will need to add
-`ro_segment_workaround_for_valgrind=true` to `args.gn` to get symbols to
-correctly appear.
-
 ## Waterfall
 
 The current health of the source tree can be found
diff --git a/docs/safetynet.md b/docs/safetynet.md
index bd0a791..8121bbc 100644
--- a/docs/safetynet.md
+++ b/docs/safetynet.md
@@ -106,9 +106,6 @@
 $ valgrind
 ```
 
-Add `ro_segment_workaround_for_valgrind=true` to `args.gn` for symbols to appear
-correctly.
-
 This is a slow and accurate profiler. Expect variations of around 100
 instructions. However, this takes about 50 times longer to run than perf stat.