Silence nds32 pic warnings

Fixes:
FAIL: Build pr22471a.so
FAIL: Build pr22471b.so
FAIL: Build pr22649-1.so
FAIL: Build pr22649-2c.so
FAIL: Build pr22649-2d.so
FAIL: PR ld/20828 dynamic symbols with section GC (auxiliary shared library)
FAIL: PR ld/20828 dynamic symbols with section GC (plain)
FAIL: PR ld/20828 dynamic symbols with section GC (version script)
FAIL: PR ld/20828 dynamic symbols with section GC (versioned shared library)
FAIL: PR ld/20828 dynamic symbols with section GC (versioned)
FAIL: PR ld/21233 dynamic symbols with section GC (auxiliary shared library)
FAIL: Build pr22150.so
FAIL: Build shared library for pr14170
FAIL: PR ld/21703 shared
FAIL: Build shared library for broken linker script test
FAIL: Build pr17068.so
FAIL: -Bsymbolic-functions
FAIL: Build pr20995.so
FAIL: Build pr20995-2.so
FAIL: Build pr22374 shared library

	* testsuite/ld-elf/shared.exp (AFLAGS_PIC): Add -mpic for nds32.

ld/ChangeLog

@@ -1,3 +1,7 @@
+2018-04-11  Alan Modra  <amodra@gmail.com>
+
+	* testsuite/ld-elf/shared.exp (AFLAGS_PIC): Add -mpic for nds32.
+
 2018-04-09  Alan Modra  <amodra@gmail.com>
 
 	* po/BLD-POTFILES.in: Regenerate.

ld/testsuite/ld-elf/shared.exp

@@ -39,6 +39,9 @@ set old_ASFLAGS $ASFLAGS
 # This target requires extra GAS options when building code for shared
 # libraries.
 set AFLAGS_PIC ""
+if [istarget "nds32*-*"] {
+    append AFLAGS_PIC " -mpic"
+}
 if [istarget "tic6x-*-*"] {
     append AFLAGS_PIC " -mpic -mpid=near"
 }