[opencv2] no absolute paths (#28180)

ports/opencv2/portfile.cmake

@@ -161,6 +161,6 @@ file(REMOVE "${CURRENT_PACKAGES_DIR}/debug/LICENSE")
 
 vcpkg_fixup_pkgconfig()
 
-configure_file("${CURRENT_PORT_DIR}/usage.in" "${CURRENT_PACKAGES_DIR}/share/${PORT}/usage")
+configure_file("${CURRENT_PORT_DIR}/usage.in" "${CURRENT_PACKAGES_DIR}/share/${PORT}/usage" @ONLY)
 
 file(INSTALL "${SOURCE_PATH}/LICENSE" DESTINATION "${CURRENT_PACKAGES_DIR}/share/${PORT}" RENAME copyright)

ports/opencv2/usage.in

@@ -1,4 +1,4 @@
-The package ${PORT} is compatible with CMake if you set the OpenCV_DIR *before* the find_package call
+The package @PORT@ is compatible with CMake if you set the OpenCV_DIR *before* the find_package call
 
-    set(OpenCV_DIR "${CURRENT_INSTALLED_DIR}/share/${PORT}")
+    set(OpenCV_DIR "${VCPKG_INSTALLED_DIR}/@TARGET_TRIPLET@/share/@PORT@")
     find_package(OpenCV REQUIRED)

ports/opencv2/vcpkg.json

@@ -1,7 +1,7 @@
 {
   "name": "opencv2",
   "version": "2.4.13.7",
-  "port-version": 15,
+  "port-version": 16,
   "description": "Open Source Computer Vision Library",
   "homepage": "https://github.com/opencv/opencv",
   "license": "BSD-3-Clause",

versions/baseline.json

@@ -5474,7 +5474,7 @@
     },
     "opencv2": {
       "baseline": "2.4.13.7",
-      "port-version": 15
+      "port-version": 16
     },
     "opencv3": {
       "baseline": "3.4.18",

versions/o-/opencv2.json

@@ -1,5 +1,10 @@
 {
   "versions": [
+    {
+      "git-tree": "27ef38b20b5788492a6a27370160f435b7d71502",
+      "version": "2.4.13.7",
+      "port-version": 16
+    },
     {
       "git-tree": "2c74bb03ea3451c670c4ec82b3a1acda11baeaf6",
       "version": "2.4.13.7",