Improve handling of bundled ICU components

We are just installing a mode file.

gn.spec

@@ -1,5 +1,6 @@
 # Build HTML docs from markdown using pandoc?
-%bcond_without html_docs
+# Currently, neither pandoc nor parallel is available in EPEL9.
+%bcond_with html_docs
 
 Name:           gn
 # Upstream uses the number of commits in the git history as the version number.
@@ -47,12 +48,15 @@ Source1:        last_commit_position.h
 Source2:        update-version
 
 # Stop overriding optimization flags
-Patch0:         gn-0153d369-no-O3.patch
+Patch:          gn-0153d369-no-O3.patch
 
 BuildRequires:  python3-devel
 BuildRequires:  ninja-build
 BuildRequires:  gcc-c++
 
+# For RPM macros:
+BuildRequires:  emacs-common
+
 %if %{with html_docs}
 BuildRequires:  pandoc
 BuildRequires:  parallel
@@ -63,10 +67,22 @@ Requires:       vim-filesystem
 Requires:       python3
 Provides:       vim-gn = %{version}-%{release}
 
-BuildRequires:  emacs
 Requires:       emacs-filesystem >= %{_emacs_version}
 Provides:       emacs-gn = %{version}-%{release}
 
+# src/base/third_party/icu/icu_utf.h:
+#
+#   This file has the relevant components from ICU copied to handle basic
+#   UTF8/16/32 conversions. Components are copied from umachine.h, utf.h,
+#   utf8.h, and utf16.h into icu_utf.h.
+#
+# The forked, bundled ICU components are copied from Chromium. Because of the
+# downstream changes (primarily, changing namespaces and symbol prefixes),
+# there is no clear path to unbundling.
+#
+# See src/base/third_party/icu/README.chromium, from which the version number
+# is taken.
+Provides:       bundled(icu) = 60
 
 %description
 GN is a meta-build system that generates build files for Ninja.
@@ -168,7 +184,7 @@ grep -E '^#define[[:blank:]]+LAST_COMMIT_POSITION[[:blank:]]+'\
 
 
 %files doc
-%license LICENSE
+%license LICENSE src/base/third_party/icu/README.chromium
 %doc AUTHORS
 %doc OWNERS
 %doc README*.md