buildgcc: Update and fix GDB

GDB stopped building ever since we updated from version 7.6
but nobody noticed ;)
Update from 7.9 to 7.9.1 and bring the required patches forward.

Change-Id: I2f357525a46d5540e9f57b80d830943bbd5dfcaf
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/10494
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <edward.ocallaghan@koparo.com>
diff --git a/util/crossgcc/patches/gdb-7.9.1_pythonhome.patch b/util/crossgcc/patches/gdb-7.9.1_pythonhome.patch
new file mode 100644
index 0000000..7e34c7a
--- /dev/null
+++ b/util/crossgcc/patches/gdb-7.9.1_pythonhome.patch
@@ -0,0 +1,19 @@
+diff -ur gdb-7.9.1/gdb/python/python.c gdb-7.9.1.patched/gdb/python/python.c
+--- gdb-7.9.1/gdb/python/python.c	2015-05-13 10:36:05.000000000 -0700
++++ gdb-7.9.1.patched/gdb/python/python.c	2015-06-09 13:13:24.824178760 -0700
+@@ -1681,6 +1681,15 @@
+ #endif
+ #endif
+ 
++  char readlinkbuffer[BUFSIZ];
++  int readlinks = readlink("/proc/self/exe", readlinkbuffer, BUFSIZ - 1);
++  readlinkbuffer[readlinks] = 0;
++  char *executeablepath = dirname(readlinkbuffer);
++  char *pythonhome = malloc(strlen(executeablepath) + strlen("/../") + 2);
++  strcpy(pythonhome, executeablepath);
++  strcat(pythonhome, "/../");
++  setenv("PYTHONHOME", pythonhome, 1);
++
+   Py_Initialize ();
+   PyEval_InitThreads ();
+