Fixed wpi_setErrnoError to print the error name

Previously, wpi_setErrnoError and wpi_setErrnoErrorWithContext
always printed "Unknown errno" whenever a C library error
occured.

Change-Id: Ib235138eea0e83b0d7462dfd6e834e3499e3b0c5

hal/lib/Athena/cpp/StackTrace.cpp

@@ -7,7 +7,3 @@
 void printCurrentStackTrace() {
   // TODO: Implement
 }
-
-bool getErrnoToName(int32_t errNo, char* name) {
-	return false; // TODO: Implement
-}