Avoid .symver on common symbols [BZ #21666]

Avoid .symver on common symbols [BZ #21666]

The .symver directive on common symbol just creates a new common symbol,
not an alias and the newer assembler with the bug fix for

https://sourceware.org/bugzilla/show_bug.cgi?id=21661

will issue an error.  Before the fix, we got

$ readelf -sW libc.so | grep "loc[12s]"
  5109: 00000000003a0608     8 OBJECT  LOCAL  DEFAULT   36 loc1
  5188: 00000000003a0610     8 OBJECT  LOCAL  DEFAULT   36 loc2
  5455: 00000000003a0618     8 OBJECT  LOCAL  DEFAULT   36 locs
  6575: 00000000003a05f0     8 OBJECT  GLOBAL DEFAULT   36 locs@GLIBC_2.2.5
  7156: 00000000003a05f8     8 OBJECT  GLOBAL DEFAULT   36 loc1@GLIBC_2.2.5
  7312: 00000000003a0600     8 OBJECT  GLOBAL DEFAULT   36 loc2@GLIBC_2.2.5

in libc.so.  The versioned loc1, loc2 and locs have the wrong addresses.
After the fix, we got

$ readelf -sW libc.so | grep "loc[12s]"
  6570: 000000000039e3b8     8 OBJECT  GLOBAL DEFAULT   34 locs@GLIBC_2.2.5
  7151: 000000000039e3c8     8 OBJECT  GLOBAL DEFAULT   34 loc1@GLIBC_2.2.5
  7307: 000000000039e3c0     8 OBJECT  GLOBAL DEFAULT   34 loc2@GLIBC_2.2.5

	[BZ #21666]
	* misc/regexp.c (loc1): Add __attribute__ ((nocommon));
	(loc2): Likewise.
	(locs): Likewise.