Moving options -Wall before extra_cxx_flags to resolve conflicting -Wno-XXX options for clang

[troy4eg]

Example:

int main() {
  int a = 7;
  int b;
  b = 10;
  return 0;
}

Output with -Wall:

$clang++-16 main.cpp -Wall
main.cpp:4:7: warning: unused variable 'a' [-Wunused-variable]
int a = 7;
^
main.cpp:5:7: warning: variable 'b' set but not used [-Wunused-but-set-variable]
int b;
^
2 warnings generated.

Output with -Wno-XXX and -Wall at the end:

$clang++-16 main.cpp -Wno-unused-variable -Wno-unused-but-set-variable -Wall
main.cpp:4:7: warning: unused variable 'a' [-Wunused-variable]
int a = 7;
^
main.cpp:5:7: warning: variable 'b' set but not used [-Wunused-but-set-variable]
int b;
^
2 warnings generated.

But if -Wall is before the other -Wno-XXX arguments, everything is compiled successfully