Patching the static library fully would need extensive changes.
Patching it out from install means it won't be included in generated cmake config files.
--- a/cmake/aom_install.cmake
+++ b/cmake/aom_install.cmake
@@ -81,7 +81,7 @@ macro(setup_aom_install_targets)
     endif()
 
     if(BUILD_SHARED_LIBS)
-      set(AOM_INSTALL_LIBS aom aom_static)
+      set(AOM_INSTALL_LIBS aom)
     else()
       set(AOM_INSTALL_LIBS aom)
     endif()