Do not accidentally include in-tree readline headers

PR build/17077 points out that when --with-system-readline is given,
gdb will still pick up the in-tree readline headers.  Normally this is
not a big problem, because readline is very stable and so the ABI does
not change much; but it is clearly a bug to do this, and could bite at
some point.

The basic problem is that OPCODES_CFLAGS uses -I$(OPCODES_SRC)/..  so
that #include "opcodes/..." works.  However, this also makes it so the

This patch fixes the problem in a mildly hacky way: remove the
offending -I option, and change gdb to use #include "../opcodes/..."
instead.  This continues to make it clear where the header comes from,
without allowing incorrect behavior.

Tested by rebuilding and then looking at the *.Po files.

gdb/ChangeLog
2018-10-06  Tom Tromey  <tom@tromey.com>

	PR build/17077:
	* Makefile.in (OPCODES_CFLAGS): Remove "-I$(OPCODES_SRC)/..".
	* arc-tdep.c, frv-tdep.c, lm32-tdep.c, mep-tdep.c,
	microblaze-tdep.c, or1k-tdep.h: Use ../opcodes, not opcodes, in
	#include.

8 files changed, 18 insertions, 11 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index e6f821d..0454d15 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,13 @@
 2018-10-06  Tom Tromey  <tom@tromey.com>
 
+	PR build/17077:
+	* Makefile.in (OPCODES_CFLAGS): Remove "-I$(OPCODES_SRC)/..".
+	* arc-tdep.c, frv-tdep.c, lm32-tdep.c, mep-tdep.c,
+	microblaze-tdep.c, or1k-tdep.h: Use ../opcodes, not opcodes, in
+	#include.
+
+2018-10-06  Tom Tromey  <tom@tromey.com>
+
 	* python/py-breakpoint.c (bppy_get_location): Handle a
 	bp_breakpoint without a location.
 
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 8d780ac..5b3a952 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -446,8 +446,7 @@ OPCODES = $(OPCODES_DIR)/libopcodes.a
 # Where are the other opcode tables which only have header file
 # versions?
 OP_INCLUDE = $(INCLUDE_DIR)/opcode
-# Some source files like to use #include "opcodes/file.h"
-OPCODES_CFLAGS = -I$(OP_INCLUDE) -I$(OPCODES_SRC)/..
+OPCODES_CFLAGS = -I$(OP_INCLUDE)
 
 # The simulator is usually nonexistent; targets that include one
 # should set this to list all the .o or .a files to be linked in.
diff --git a/gdb/arc-tdep.c b/gdb/arc-tdep.c
index fad9170..b9dcbbc 100644
--- a/gdb/arc-tdep.c
+++ b/gdb/arc-tdep.c
@@ -33,7 +33,7 @@
 
 /* ARC header files.  */
 #include "opcode/arc.h"
-#include "opcodes/arc-dis.h"
+#include "../opcodes/arc-dis.h"
 #include "arc-tdep.h"
 
 /* Standard headers.  */
diff --git a/gdb/frv-tdep.c b/gdb/frv-tdep.c
index 1eed441..dafab75 100644
--- a/gdb/frv-tdep.c
+++ b/gdb/frv-tdep.c
@@ -29,7 +29,7 @@
 #include "dis-asm.h"
 #include "sim-regno.h"
 #include "gdb/sim-frv.h"
-#include "opcodes/frv-desc.h"	/* for the H_SPR_... enums */
+#include "../opcodes/frv-desc.h"	/* for the H_SPR_... enums */
 #include "symtab.h"
 #include "elf-bfd.h"
 #include "elf/frv.h"
diff --git a/gdb/lm32-tdep.c b/gdb/lm32-tdep.c
index 9428521..694d30ee 100644
--- a/gdb/lm32-tdep.c
+++ b/gdb/lm32-tdep.c
@@ -35,7 +35,7 @@
 #include "regcache.h"
 #include "trad-frame.h"
 #include "reggroups.h"
-#include "opcodes/lm32-desc.h"
+#include "../opcodes/lm32-desc.h"
 #include <algorithm>
 
 /* Macros to extract fields from an instruction.  */
diff --git a/gdb/mep-tdep.c b/gdb/mep-tdep.c
index 4b5bfcb..ae9c4de 100644
--- a/gdb/mep-tdep.c
+++ b/gdb/mep-tdep.c
@@ -48,8 +48,8 @@
 
 /* Get the user's customized MeP coprocessor register names from
    libopcodes.  */
-#include "opcodes/mep-desc.h"
-#include "opcodes/mep-opc.h"
+#include "../opcodes/mep-desc.h"
+#include "../opcodes/mep-opc.h"
 
 
 /* The gdbarch_tdep structure.  */
diff --git a/gdb/microblaze-tdep.c b/gdb/microblaze-tdep.c
index 4dbfd1b..018b713 100644
--- a/gdb/microblaze-tdep.c
+++ b/gdb/microblaze-tdep.c
@@ -34,8 +34,8 @@
 #include "dwarf2-frame.h"
 #include "osabi.h"
 #include "target-descriptions.h"
-#include "opcodes/microblaze-opcm.h"
-#include "opcodes/microblaze-dis.h"
+#include "../opcodes/microblaze-opcm.h"
+#include "../opcodes/microblaze-dis.h"
 #include "microblaze-tdep.h"
 #include "remote.h"
 
diff --git a/gdb/or1k-tdep.h b/gdb/or1k-tdep.h
index 4a93540..b630c77 100644
--- a/gdb/or1k-tdep.h
+++ b/gdb/or1k-tdep.h
@@ -24,8 +24,8 @@
 #define TARGET_OR1K
 #endif
 
-#include "opcodes/or1k-desc.h"
-#include "opcodes/or1k-opc.h"
+#include "../opcodes/or1k-desc.h"
+#include "../opcodes/or1k-opc.h"
 
 /* General Purpose Registers */
 #define OR1K_ZERO_REGNUM          0