fix typo

From-SVN: r42112

gcc/ChangeLog

@@ -3,7 +3,7 @@
 	* rs6000.md (movdi splitter): Sign extend more efficiently.
 	* rs6000.c (reg_or_arith_cint_operand): Redefine 64-bit constant
 	to "long long" valid on 32-bit and 64-bit hosts.
-	(logical_operand): Cast trunc_int_for_mode rturn value.
+	(logical_operand): Cast trunc_int_for_mode return value.
 	(rs6000_emit_move): Shift macro to encapsulate variable.
 	(rs6000_va_start): Use HOST_WIDE_INT_PRINT_DEC.
 	(rs6000_emit_{prologue,epilogue}): EH regno is unsigned but