Fix internal error when core file section is too big

Fix internal error when core file section is too big

As reported in PR 17808, a test case with a forged (invalid) core file
can crash GDB with an assertion failure.  In that particular case the
prstatus of an i386 core file looks like that from an AMD64 core file.
Consequently the respective regset supply function i386_supply_gregset
is invoked with a larger buffer than usual.  But i386_supply_gregset
asserts a specific buffer size, and this assertion fails.

The patch relaxes all buffer size assertions in regset supply
functions such that they merely check for a sufficiently large buffer.
For consistency the regset collect functions are adjusted as well.

gdb/ChangeLog:

	PR corefiles/17808:
	* gdbarch.sh (iterate_over_regset_sections_cb): Document this
	function type, particularly its SIZE parameter.
	* gdbarch.h: Regenerate.
	* amd64-tdep.c (amd64_supply_fpregset): In gdb_assert, compare
	actual against required size using ">=" instead of "==".
	(amd64_collect_fpregset): Likewise.
	* i386-tdep.c (i386_supply_gregset): Likewise.
	(i386_collect_gregset): Likewise.
	(i386_supply_fpregset): Likewise.
	(i386_collect_fpregset): Likewise.
	* mips-linux-tdep.c (mips_supply_gregset_wrapper): Likewise.
	(mips_fill_gregset_wrapper): Likewise.
	(mips_supply_fpregset_wrapper): Likewise.
	(mips_fill_fpregset_wrapper): Likewise.
	(mips64_supply_gregset_wrapper): Likewise.
	(mips64_fill_gregset_wrapper): Likewise.
	(mips64_supply_fpregset_wrapper): Likewise.
	(mips64_fill_fpregset_wrapper): Likewise.
	* mn10300-linux-tdep.c (am33_supply_gregset_method): Likewise.
	(am33_supply_fpregset_method): Likewise.
	(am33_collect_gregset_method): Likewise.
	(am33_collect_fpregset_method): Likewise.