DWARF-5: Ignore empty range in DWARF-5 line number tables

The DWARF5 spec does indeed explicitly say: "A bounded range entry whose
beginning and ending address offsets are equal (including zero) indicates
an empty range and may be ignored."

Since arange_add already ignores empty ranges, remove the whole check
which is equivalent to the check plus explicit continue.

	PR binutils/27231
	* dwarf2.c (read_rnglists): Ignore empty range when parsing line
	number tables.

(cherry picked from commit 940d020)

Author: hjl-tools

bfd/ChangeLog

@@ -1,3 +1,9 @@
+2021-01-24  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR binutils/27231
+	* dwarf2.c (read_rnglists): Ignore empty range when parsing line
+	number tables.
+
 2021-01-24  Nick Clifton  <nickc@redhat.com>
 
 	* version.m4: Set to 2.36.0.

bfd/dwarf2.c

@@ -3289,9 +3289,6 @@ read_rnglists (struct comp_unit *unit, struct arange *arange,
 	  return FALSE;
 	}
 
-      if ((low_pc == 0 && high_pc == 0) || low_pc == high_pc)
-	return FALSE;
-
       if (!arange_add (unit, arange, low_pc, high_pc))
 	return FALSE;
     }