capi: Fix testing stand-alone inclusion of headers (#11882)

If headers with the same filename were in different directories their
tests would clobber each other, so this fixes the test paths and
filenames to ensure that each header is indeed tested. This then fixes
issues with `component/val.h` and `component/linker.h` to add some
missing includes.

Author: alexcrichton

crates/c-api/include/wasmtime/component/linker.h

@@ -8,6 +8,7 @@
 #include <wasmtime/component/instance.h>
 #include <wasmtime/conf.h>
 #include <wasmtime/error.h>
+#include <wasmtime/module.h>
 #include <wasmtime/store.h>
 
 #ifdef WASMTIME_FEATURE_COMPONENT_MODEL

crates/c-api/include/wasmtime/component/val.h

@@ -7,6 +7,9 @@
 
 #ifdef WASMTIME_FEATURE_COMPONENT_MODEL
 
+#include <stdint.h>
+#include <wasm.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif

crates/c-api/tests/CMakeLists.txt

@@ -68,15 +68,14 @@ foreach(header IN LISTS cpp_headers)
   if(header_extension STREQUAL ".h.in")
     continue()
   endif()
-  cmake_path(GET header FILENAME header_filename)
-  cmake_path(APPEND CMAKE_CURRENT_BINARY_DIR "header-test" "${header_filename}.cc"
-    OUTPUT_VARIABLE test_filename)
-  list(APPEND header_tests ${test_filename})
-
   cmake_path(
     RELATIVE_PATH header
     BASE_DIRECTORY ${header_root}
     OUTPUT_VARIABLE rel_header)
+  cmake_path(APPEND CMAKE_CURRENT_BINARY_DIR "header-test" "${rel_header}.cc"
+    OUTPUT_VARIABLE test_filename)
+  list(APPEND header_tests ${test_filename})
+
   file(WRITE ${test_filename} "#include <${rel_header}>")
 endforeach()
 add_capi_test(standalone-headers FILES ${header_tests})