build error due missing binary operator before token "(" 
**Describe the bug**
build error on working ancient gcc :

```
[ 94%] Building CXX object CMakeFiles/xmrig.dir/src/crypto/astrobwt/sort_indices2.cpp.o
[ 94%] /opt/xmrig/src/crypto/astrobwt/sort_indices2.cpp:40:24: error: missing binary operator before token "("
 #if __has_cpp_attribute(unlikely)
                        ^
Building C object CMakeFiles/xmrig.dir/src/crypto/astrobwt/xmm6int/salsa20_xmm6int-avx2.c.o
CMakeFiles/xmrig.dir/build.make:5528: recipe for target 'CMakeFiles/xmrig.dir/src/crypto/astrobwt/sort_indices2.cpp.o' failed
make[2]: *** [CMakeFiles/xmrig.dir/src/crypto/astrobwt/sort_indices2.cpp.o] Error 1

```

**To Reproduce**
compiling in gcc 4.8 and 4.7

**Expected behavior**
 compilation

**Required data**
 
 - OS: of course not the crap of guyindows

**Additional context**

related to #3057  
