buildgcc: Update coreboot reference toolchain to gcc 4.6.2

In addition:
- drop some unneeded patches
- make the scripting support depend on SKIPPYTHON not SKIPGDB
  so it is possible to build GDB with and without scripting support
- rename the repository checkout version of GCC trunk, not X+1
  so we don't have to change it on every version upgrade.

Change-Id: I1b7d5b8921187c1c1d39b04f20bb715ddba72fe8
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/367
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

util/crossgcc/patches/binutils-2.20.1_no-bfd-doc.patch

@@ -1,11 +0,0 @@
---- binutils-2.20.1/bfd/Makefile.in~	2010-07-25 10:56:45 +0000
-+++ binutils-2.20.1/bfd/Makefile.in	2010-07-25 10:19:24 +0000
-@@ -320,7 +320,7 @@
- # RELEASE=y
- INCDIR = $(srcdir)/../include
- CSEARCH = -I. -I$(srcdir) -I$(INCDIR)
--SUBDIRS = doc po
-+SUBDIRS = po
- bfddocdir = doc
- libbfd_la_LDFLAGS = $(am__append_1) -release `cat libtool-soversion` \
- 	@SHARED_LDFLAGS@ $(am__empty)

util/crossgcc/patches/gcc-4.5.2_pragma.patch

@@ -1,10 +0,0 @@
-diff -ur gcc-4.5.2.orig/gcc/config/i386/i386elf.h gcc-4.5.1/gcc/config/i386/i386elf.h
---- gcc-4.5.2.orig/gcc/config/i386/i386elf.h	2010-11-17 19:48:16.184401200 -0700
-+++ gcc-4.5.2/gcc/config/i386/i386elf.h	2010-11-17 20:52:54.443969900 -0700
-@@ -123,3 +123,6 @@
- #undef ASM_OUTPUT_ALIGNED_BSS
- #define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN) \
-   asm_output_aligned_bss (FILE, DECL, NAME, SIZE, ALIGN)
-+
-+/* Enable parsing of #pragma pack(push,<n>) and #pragma pack(pop).  */
-+#define HANDLE_PRAGMA_PACK_PUSH_POP 1