[WPE][CMake] Cannot complete distcheck with ENABLE_WPE_1_1_API=OFF

https://bugs.webkit.org/show_bug.cgi?id=265440

Reviewed by Michael Catanzaro.

Change which directory with documentation for the WebProcess extension
API gets packaged when creating release tarballs.

* Source/cmake/OptionsWPE.cmake: Add a new variable for name of the
  pkg-config module of the WebProcess extension API, reuse it to define
  the paths of the .pc files.
* Tools/wpe/manifest.txt.in: Change the generated WebProcess extension
  API output directory path to use the new variable.

Canonical link: https://commits.webkit.org/276496@main

Source/cmake/OptionsWPE.cmake

@@ -437,12 +437,14 @@ set(WPE_PKGCONFIG_FILE ${CMAKE_BINARY_DIR}/wpe-webkit-${WPE_API_VERSION}.pc)
 set(WPE_Uninstalled_PKGCONFIG_FILE ${CMAKE_BINARY_DIR}/wpe-webkit-${WPE_API_VERSION}-uninstalled.pc)
 
 if (ENABLE_2022_GLIB_API)
-    set(WPEWebProcessExtension_PKGCONFIG_FILE ${CMAKE_BINARY_DIR}/wpe-web-process-extension-${WPE_API_VERSION}.pc)
-    set(WPEWebProcessExtension_Uninstalled_PKGCONFIG_FILE ${CMAKE_BINARY_DIR}/wpe-web-process-extension-${WPE_API_VERSION}-uninstalled.pc)
+    set(WPE_WEB_PROCESS_EXTENSION_PC_MODULE "wpe-web-process-extension-${WPE_API_VERSION}")
 else ()
-    set(WPEWebProcessExtension_PKGCONFIG_FILE ${CMAKE_BINARY_DIR}/wpe-web-extension-${WPE_API_VERSION}.pc)
-    set(WPEWebProcessExtension_Uninstalled_PKGCONFIG_FILE ${CMAKE_BINARY_DIR}/wpe-web-extension-${WPE_API_VERSION}-uninstalled.pc)
+    set(WPE_WEB_PROCESS_EXTENSION_PC_MODULE "wpe-web-extension-${WPE_API_VERSION}")
 endif ()
+EXPOSE_STRING_VARIABLE_TO_BUILD(WPE_WEB_PROCESS_EXTENSION_PC_MODULE)
+
+set(WPEWebProcessExtension_PKGCONFIG_FILE ${CMAKE_BINARY_DIR}/${WPE_WEB_PROCESS_EXTENSION_PC_MODULE}.pc)
+set(WPEWebProcessExtension_Uninstalled_PKGCONFIG_FILE ${CMAKE_BINARY_DIR}/${WPE_WEB_PROCESS_EXTENSION_PC_MODULE}-uninstalled.pc)
 
 include(BubblewrapSandboxChecks)
 include(GStreamerChecks)

Tools/wpe/manifest.txt.in

@@ -101,4 +101,4 @@ file Tools/PlatformWPE.cmake
 
 directory ${CMAKE_BINARY_DIR}/Documentation/wpe-javascriptcore-${WPE_API_VERSION} Documentation/wpe-javascriptcore-${WPE_API_VERSION}
 directory ${CMAKE_BINARY_DIR}/Documentation/wpe-webkit-${WPE_API_VERSION} Documentation/wpe-webkit-${WPE_API_VERSION}
-directory ${CMAKE_BINARY_DIR}/Documentation/wpe-web-extension-${WPE_API_VERSION} Documentation/wpe-web-extension-${WPE_API_VERSION}
+directory ${CMAKE_BINARY_DIR}/Documentation/${WPE_WEB_PROCESS_EXTENSION_PC_MODULE} Documentation/wpe-web-extension-${WPE_API_VERSION}