Support pkg-config (#253)

cmake/cargs.cmake

@@ -2,10 +2,11 @@ function(download_cargs)
   include(FetchContent)
 
   set(cargs_URL "https://github.com/likle/cargs/archive/refs/tags/v1.0.3.tar.gz")
+  set(cargs_URL2 "https://huggingface.co/csukuangfj/sherpa-onnx-cmake-deps/resolve/main/cargs-1.0.3.tar.gz")
   set(cargs_HASH "SHA256=ddba25bd35e9c6c75bc706c126001b8ce8e084d40ef37050e6aa6963e836eb8b")
 
   # If you don't have access to the Internet,
-  # please pre-download asio
+  # please pre-download cargs
   set(possible_file_locations
     $ENV{HOME}/Downloads/cargs-1.0.3.tar.gz
     ${PROJECT_SOURCE_DIR}/cargs-1.0.3.tar.gz
@@ -19,11 +20,18 @@ function(download_cargs)
       set(cargs_URL  "${f}")
       file(TO_CMAKE_PATH "${cargs_URL}" cargs_URL)
       message(STATUS "Found local downloaded cargs: ${cargs_URL}")
+      set(cargs_URL2)
       break()
     endif()
   endforeach()
 
-  FetchContent_Declare(cargs URL ${cargs_URL} URL_HASH ${cargs_HASH})
+  FetchContent_Declare(cargs
+    URL
+      ${cargs_URL}
+      ${cargs_URL2}
+    URL_HASH
+      ${cargs_HASH}
+  )
 
   FetchContent_GetProperties(cargs)
   if(NOT cargs_POPULATED)
@@ -32,6 +40,11 @@ function(download_cargs)
   endif()
   message(STATUS "cargs is downloaded to ${cargs_SOURCE_DIR}")
   add_subdirectory(${cargs_SOURCE_DIR} ${cargs_BINARY_DIR} EXCLUDE_FROM_ALL)
+
+  install(TARGETS cargs DESTINATION lib)
+  install(FILES ${cargs_SOURCE_DIR}/include/cargs.h
+    DESTINATION include
+  )
 endfunction()
 
 download_cargs()