Take complete control of header search dirs.

gcc/config/m68k/amigaos.h

@@ -22,6 +22,16 @@ Boston, MA 02111-1307, USA.  */
 
 #include "m68k/m68k.h"
 
+#undef INCLUDE_DEFAULTS
+#define INCLUDE_DEFAULTS                                    \
+  {                                                         \
+    { GPLUSPLUS_INCLUDE_DIR, "G++", 1, 1 },                 \
+    { GCC_INCLUDE_DIR, "GCC", 0, 0 },                       \
+    { TOOL_INCLUDE_DIR, "GCC", 0, 0 },                      \
+    { TOOL_INCLUDE_DIR "/../../os-include", "GCC", 0, 0 },  \
+    { 0, 0, 0, 0 }                                          \
+  }
+
 /* begin-GG-local: explicit register specification for parameters */
 #define TARGET_AMIGAOS
 /* end-GG-local */

gcc/config/m68k/t-amigaos

@@ -1,12 +1,5 @@
 # Makefile fragment for AmigaOS target.
 
-# Each compilation environment (Manx, Dice, GCC, SAS/C, etc) provides its
-# own equivalent of the UNIX /usr/include tree.  For gcc, the standard headers
-# are in /gg/include and system specific headers are in /gg/os-include.
-# Use these paths for fixincludes.
-
-SYSTEM_HEADER_DIR = /gg/include
-
 # Extra object file linked to the cc1* executables.
 amigaos.o: $(srcdir)/config/m68k/amigaos.c $(CONFIG_H)
 	$(CC) -c $(ALL_CFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) $<