Library files aren't supposed to be executable

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

ChangeLog.d/cmake-install.txt

@@ -0,0 +1,3 @@
+Bugfix
+   * Library files installed after a CMake build no longer have execute
+     permission.

library/CMakeLists.txt

@@ -201,7 +201,7 @@ foreach(target IN LISTS target_libraries)
         PRIVATE ${thirdparty_def})
     install(TARGETS ${target}
             DESTINATION ${LIB_INSTALL_DIR}
-            PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
+            PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ)
 endforeach(target)
 
 add_custom_target(lib DEPENDS mbedcrypto mbedx509 mbedtls)