Add dynamic linker support for uClibc

Signed-off-by: Waldemar Brodkorb <wbx@uclibc-ng.org>

diff -Nur gcc-5.3.0.orig/gcc/config/microblaze/linux.h gcc-5.3.0/gcc/config/microblaze/linux.h
--- gcc-5.3.0.orig/gcc/config/microblaze/linux.h	2015-05-28 16:08:19.000000000 +0200
+++ gcc-5.3.0/gcc/config/microblaze/linux.h	2016-05-13 09:21:01.579262885 +0200
@@ -28,7 +28,15 @@
 #undef TLS_NEEDS_GOT
 #define TLS_NEEDS_GOT 1
 
-#define DYNAMIC_LINKER "/lib/ld.so.1"
+#define GLIBC_DYNAMIC_LINKER	"/lib/ld.so.1"
+#define UCLIBC_DYNAMIC_LINKER "/lib/ld-uClibc.so.0"
+
+#if DEFAULT_LIBC == LIBC_UCLIBC
+#define DYNAMIC_LINKER UCLIBC_DYNAMIC_LINKER
+#else
+#define DYNAMIC_LINKER GLIBC_DYNAMIC_LINKER
+#endif
+
 #undef  SUBTARGET_EXTRA_SPECS
 #define SUBTARGET_EXTRA_SPECS \
   { "dynamic_linker", DYNAMIC_LINKER }