Merge pull request #9622 from skylersaleh/fix_zstd_headers

Check that zstd headers can be found before using a shared zstd library

CMakeLists.txt

@@ -615,11 +615,16 @@ else()
 endif()
 
 pkg_check_modules(ZSTD QUIET libzstd>=1.4.0)
-if(ZSTD_FOUND)
+check_include_file(zstd.h HAVE_ZSTD_H)
+if(ZSTD_FOUND AND HAVE_ZSTD_H)
   message(STATUS "Using shared zstd version: " ${ZSTD_VERSION})
 else()
   check_vendoring_approved(zstd)
-  message(STATUS "Shared zstd not found, falling back to the static library")
+  if(ZSTD_FOUND AND NOT HAVE_ZSTD_H)
+    message(STATUS "Shared zstd found but lacks headers, falling back to the static library")
+  else()
+    message(STATUS "Shared zstd not found, falling back to the static library")
+  endif()
   add_subdirectory(Externals/zstd)
 endif()