use gcc __atomic_{load,store} with clang
use gcc __atomic_{load,store} with clang

use gcc __atomic_{load,store} with clang instead of clang C11 builtins
__c11_atomic_{load,store}() since these builtins require _Atomic type
(clang atomic builtins have stricter compliance to C11 spec)

gstrauss/plasma,gstrauss/plasma