Fix clang build with libstdc++8

Chromium was trying to use some specific sample profiles, just ignore
that.

Task-number: QTBUG-75265
Change-Id: Ifd0517d521634ec01f66d18606f8696bf703b42a
Reviewed-by: Michal Klocek <michal.klocek@qt.io>

src/core/config/linux.pri

@@ -36,6 +36,7 @@ clang {
     gn_args += \
         is_clang=true \
         clang_use_chrome_plugins=false \
+        clang_use_default_sample_profile=false \
         clang_base_path=\"$${clang_prefix}\"
 
     linux-clang-libc++: gn_args += use_libcxx=true