Remove unnecessary abs() calls

Literal cannot be negative at this point

src/Composer/DependencyResolver/Solver.php

@@ -796,10 +796,10 @@ class Solver
                             continue 2; // next rule
                         }
                     } else {
-                        if ($this->decisions->decidedInstall(abs($literal))) {
+                        if ($this->decisions->decidedInstall($literal)) {
                             continue 2; // next rule
                         }
-                        if ($this->decisions->undecided(abs($literal))) {
+                        if ($this->decisions->undecided($literal)) {
                             $decisionQueue[] = $literal;
                         }
                     }