gcc: xtensa: don't force PIC for uclinux target

xtensa-uclinux uses bFLT executable file format that cannot relocate
fields representing offsets from data to code. C++ objects built as PIC
use offsets to encode FDE structures. As a result C++ exception handling
doesn't work correctly on xtensa-uclinux. Don't use PIC by default on
xtensa-uclinux.

gcc/
2018-11-05  Max Filippov  <jcmvbkbc@gmail.com>

	* config/xtensa/uclinux.h (XTENSA_ALWAYS_PIC): Change to 0.

From-SVN: r265823

gcc/ChangeLog

+2018-11-05  Max Filippov  <jcmvbkbc@gmail.com>
+
+	* config/xtensa/uclinux.h (XTENSA_ALWAYS_PIC): Change to 0.
+
 2018-11-05  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	PR rtl-optimization/87871

gcc/config/xtensa/uclinux.h

@@ -59,8 +59,8 @@ along with GCC; see the file COPYING3.  If not see
 #undef LOCAL_LABEL_PREFIX
 #define LOCAL_LABEL_PREFIX	"."
 
-/* Always enable "-fpic" for Xtensa Linux.  */
-#define XTENSA_ALWAYS_PIC 1
+/* Don't enable "-fpic" for Xtensa uclinux.  */
+#define XTENSA_ALWAYS_PIC 0
 
 #undef TARGET_LIBC_HAS_FUNCTION
 #define TARGET_LIBC_HAS_FUNCTION no_c99_libc_has_function