[icu] Add reminder to install autoconf-archive (#38019)

Fixes #38005.
By user request, add a reminder to install `autoconf-archive` on
non-windows machines.

- [x] Changes comply with the [maintainer
guide](https://github.com/microsoft/vcpkg-docs/blob/main/vcpkg/contributing/maintainer-guide.md).
- [ ] ~SHA512s are updated for each updated download.~
- [ ] ~The "supports" clause reflects platforms that may be fixed by
this new version.~
- [ ] ·Any fixed [CI
baseline](https://github.com/microsoft/vcpkg/blob/master/scripts/ci.baseline.txt)
entries are removed from that file.~
- [ ] ~Any patches that are no longer applied are deleted from the
port's directory.~
- [x] The version database is fixed by rerunning `./vcpkg x-add-version
--all` and committing the result.
- [x] Only one version is added to each modified port's versions file.

---------

Co-authored-by: Monica <v-liumonica@microsoft.com>

ports/icu/portfile.cmake

@@ -1,3 +1,18 @@
+if(NOT VCPKG_TARGET_IS_WINDOWS)
+    message(WARNING "${PORT} currently requires the following programs from the system package manager:
+    autoconf automake autoconf-archive
+On Debian and Ubuntu derivatives:
+    sudo apt-get install autoconf automake autoconf-archive
+On recent Red Hat and Fedora derivatives:
+    sudo dnf install autoconf automake autoconf-archive
+On Arch Linux and derivatives:
+    sudo pacman -S autoconf automake autoconf-archive
+On Alpine:
+    apk add autoconf automake autoconf-archive
+On macOS:
+    brew install autoconf automake autoconf-archive\n")
+endif()
+
 string(REGEX MATCH "^[0-9]*" ICU_VERSION_MAJOR "${VERSION}")
 string(REPLACE "." "_" VERSION2 "${VERSION}")
 string(REPLACE "." "-" VERSION3 "${VERSION}")

ports/icu/vcpkg.json

@@ -1,7 +1,7 @@
 {
   "name": "icu",
   "version": "74.2",
-  "port-version": 1,
+  "port-version": 2,
   "description": "Mature and widely used Unicode and localization library.",
   "homepage": "https://icu.unicode.org/home",
   "license": "ICU",

versions/baseline.json

@@ -3474,7 +3474,7 @@
     },
     "icu": {
       "baseline": "74.2",
-      "port-version": 1
+      "port-version": 2
     },
     "ideviceinstaller": {
       "baseline": "2023-07-21",

versions/i-/icu.json

@@ -1,5 +1,10 @@
 {
   "versions": [
+    {
+      "git-tree": "a36199768fe1f9676b61d5d28ed9ac36c9f041c0",
+      "version": "74.2",
+      "port-version": 2
+    },
     {
       "git-tree": "dd30ff59dbfac290a1547dccc5ba44646fffa018",
       "version": "74.2",