fix vendoring attribute (#7155)

Expand out the file extensions for vendored code so git reports the
status correctly

.gitattributes

 llm/ext_server/* linguist-vendored
-llama/**/*.{cpp,hpp,h,c,cu,cuh,m} linguist-vendored
+llama/**/*.cpp linguist-vendored
+llama/**/*.hpp linguist-vendored
+llama/**/*.h linguist-vendored
+llama/**/*.c linguist-vendored
+llama/**/*.cu linguist-vendored
+llama/**/*.cuh linguist-vendored
+llama/**/*.m linguist-vendored
 
 * text=auto
 *.go text eol=lf