Merge bitcoin/bitcoin#27872: build: suppress external warnings by default

3b2acfc build: suppress external warnings by default (fanquake)

Pull request description:

  I think we are at the point where it make more sense to make this the default, than not. It's already used in the CI, and I assume most building locally are also utilising it.

ACKs for top commit:
  achow101:
    ACK 3b2acfc
  hebasto:
    ACK 3b2acfc
  stickies-v:
    ACK 3b2acfc

Tree-SHA512: be20203381c03dea8b5d64876c56bf8bb8defdfd6fc6d5398b71d3f28d0209c4bd1374f108df708aaa8867fda818a9bc611d1908c9fbb74f8cccdfbc5aff05af

Author: achow101

ci/test/06_script_b.sh

@@ -67,7 +67,7 @@ if [ "$DOWNLOAD_PREVIOUS_RELEASES" = "true" ]; then
   test/get_previous_releases.py -b -t "$PREVIOUS_RELEASES_DIR"
 fi
 
-BITCOIN_CONFIG_ALL="--enable-suppress-external-warnings --disable-dependency-tracking"
+BITCOIN_CONFIG_ALL="--disable-dependency-tracking"
 if [ -z "$NO_DEPENDS" ]; then
   BITCOIN_CONFIG_ALL="${BITCOIN_CONFIG_ALL} CONFIG_SITE=$DEPENDS_DIR/$HOST/share/config.site"
 fi

configure.ac

@@ -244,10 +244,10 @@ dnl May be useful if warnings from external headers clutter the build output
 dnl too much, so that it becomes difficult to spot Bitcoin Core warnings
 dnl or if they cause a build failure with --enable-werror.
 AC_ARG_ENABLE([suppress-external-warnings],
-  [AS_HELP_STRING([--enable-suppress-external-warnings],
-                  [Suppress warnings from external headers (default is no)])],
+  [AS_HELP_STRING([--disable-suppress-external-warnings],
+                  [Do not suppress warnings from external headers (default is to suppress)])],
   [suppress_external_warnings=$enableval],
-  [suppress_external_warnings=no])
+  [suppress_external_warnings=yes])
 
 AC_ARG_ENABLE([lcov],
   [AS_HELP_STRING([--enable-lcov],

doc/developer-notes.md

@@ -217,13 +217,11 @@ apt install clang-tidy bear clang
 Then, pass clang as compiler to configure, and use bear to produce the `compile_commands.json`:
 
 ```sh
-./autogen.sh && ./configure CC=clang CXX=clang++ --enable-suppress-external-warnings
+./autogen.sh && ./configure CC=clang CXX=clang++
 make clean && bear --config src/.bear-tidy-config -- make -j $(nproc)
 ```
 
-The output is denoised of errors from external dependencies and includes with
-`--enable-suppress-external-warnings` and `--config src/.bear-tidy-config`. Both
-options may be omitted to view the full list of errors.
+The output is denoised of errors from external dependencies.
 
 To run clang-tidy on all source files: