Allow target to override gnu-user.h crti and crtn

Also give target access to the gnu-user.h LINK_GCC_C_SEQUENCE_SPEC.

	* config/gnu-user.h (GNU_USER_TARGET_CRTI): Define.
	(GNU_USER_TARGET_STARTFILE_SPEC): Use it here.
	(GNU_USER_TARGET_CRTN): Define.
	(GNU_USER_TARGET_ENDFILE_SPEC): Use it here.
	(GNU_USER_TARGET_LINK_GCC_C_SEQUENCE_SPEC): Define.

From-SVN: r266250

gcc/ChangeLog

 2018-11-18  Alan Modra  <amodra@gmail.com>
 
+	* config/gnu-user.h (GNU_USER_TARGET_CRTI): Define.
+	(GNU_USER_TARGET_STARTFILE_SPEC): Use it here.
+	(GNU_USER_TARGET_CRTN): Define.
+	(GNU_USER_TARGET_ENDFILE_SPEC): Use it here.
+	(GNU_USER_TARGET_LINK_GCC_C_SEQUENCE_SPEC): Define.
+
+2018-11-18  Alan Modra  <amodra@gmail.com>
+
 	* config/gnu-user.h (GNU_USER_TARGET_STARTFILE_SPEC): Delete
 	!HAVE_LD_PIE variant.
 	(GNU_USER_TARGET_ENDFILE_SPEC): Likewise.

gcc/config/gnu-user.h

@@ -40,6 +40,9 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define CRTOFFLOADEND ""
 #endif
 
+#define GNU_USER_TARGET_CRTI "crti.o%s"
+#define GNU_USER_TARGET_CRTN "crtn.o%s"
+
 /* Provide a STARTFILE_SPEC appropriate for GNU userspace.  Here we add
    the GNU userspace magical crtbegin.o file (see crtstuff.c) which
    provides part of the support for getting C++ file-scope static
@@ -51,8 +54,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      static:crt1.o%s; \
      static-pie:rcrt1.o%s; \
      " PIE_SPEC ":Scrt1.o%s; \
-     :crt1.o%s} \
-   crti.o%s \
+     :crt1.o%s} " \
+   GNU_USER_TARGET_CRTI " \
    %{static:crtbeginT.o%s; \
      shared|static-pie|" PIE_SPEC ":crtbeginS.o%s; \
      :crtbegin.o%s} \
@@ -75,8 +78,8 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      fvtable-verify=std:vtv_end.o%s} \
    %{static:crtend.o%s; \
      shared|static-pie|" PIE_SPEC ":crtendS.o%s; \
-     :crtend.o%s} \
-   crtn.o%s " \
+     :crtend.o%s} " \
+   GNU_USER_TARGET_CRTN " " \
    CRTOFFLOADEND
 #undef  ENDFILE_SPEC
 #define ENDFILE_SPEC GNU_USER_TARGET_ENDFILE_SPEC
@@ -106,11 +109,13 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define LINK_EH_SPEC "%{!static|static-pie:--eh-frame-hdr} "
 #endif
 
-#undef LINK_GCC_C_SEQUENCE_SPEC
-#define LINK_GCC_C_SEQUENCE_SPEC \
+#define GNU_USER_TARGET_LINK_GCC_C_SEQUENCE_SPEC \
   "%{static|static-pie:--start-group} %G %{!nolibc:%L} \
    %{static|static-pie:--end-group}%{!static:%{!static-pie:%G}}"
 
+#undef LINK_GCC_C_SEQUENCE_SPEC
+#define LINK_GCC_C_SEQUENCE_SPEC GNU_USER_TARGET_LINK_GCC_C_SEQUENCE_SPEC
+
 /* Use --as-needed -lgcc_s for eh support.  */
 #ifdef HAVE_LD_AS_NEEDED
 #define USE_LD_AS_NEEDED 1