Don't lint headers using ClangTidy (sourcemeta#1686)

See: sourcemeta#1645
Signed-off-by: Juan Cruz Viotti <[email protected]>

Author: jviotti

CMakeLists.txt

@@ -96,8 +96,7 @@ if(PROJECT_IS_TOP_LEVEL)
     src/*.h src/*.cc
     benchmark/*.h benchmark/*.cc
     test/*.h test/*.cc)
-  sourcemeta_target_clang_tidy(SOURCES
-    src/*.h src/*.cc)
+  sourcemeta_target_clang_tidy(SOURCES src/*.cc)
 endif()
 
 # Testing