linux-user: Define ELF_ET_DYN_BASE in $guest/target_mman.h

Copy each guest kernel's default value, then bound it
against reserved_va or the host address space.

Tested-by: Helge Deller <deller@gmx.de>
Reviewed-by: Helge Deller <deller@gmx.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

linux-user/ppc/target_mman.h

@@ -17,6 +17,13 @@
 #define TASK_UNMAPPED_BASE      0x40000000
 #endif
 
+/* arch/powerpc/include/asm/elf.h */
+#ifdef TARGET_PPC64
+#define ELF_ET_DYN_BASE         0x100000000ull
+#else
+#define ELF_ET_DYN_BASE         0x000400000
+#endif
+
 #include "../generic/target_mman.h"
 
 #endif