kernel-2.eclass: Remove < 2.6 support for kernel headers

The functionality removed is only to support kernels
< 2.6 These kernels have long been removed from the tree

Detail:
Remove the function compile_headers as it is not called
for kernels > 2.6.18 because that's when the build target
headers_install was introduced.
Remove supporting function compile_headers_tweak_config.
Additionally, remove 2.6 support from install_headers.

Signed-off-by: Mike Pagano <mpagano@gentoo.org>
---
eclass/kernel-2.eclass | 112 ++---------------------------------------
1 file changed, 5 insertions(+), 107 deletions(-)

diff --git a/eclass/kernel-2.eclass b/eclass/kernel-2.eclass
index ef70e250c..983ba9169 100644
--- a/eclass/kernel-2.eclass
+++ b/eclass/kernel-2.eclass
@@ -759,83 +759,6 @@ unpack_fix_install_path() {
sed -i -e 's:#export\tINSTALL_PATH:export\tINSTALL_PATH:' "${S}"/Makefile || die
}

-# Compile Functions
-
-# @FUNCTION: compile_headers
-# @USAGE:
-# @DESCRIPTION:
-# header compilation
-
-compile_headers() {
- env_setup_xmakeopts
-
- # if we couldnt obtain HOSTCFLAGS from the Makefile,
- # then set it to something sane
- local HOSTCFLAGS=$(getfilevar HOSTCFLAGS "${S}"/Makefile)
- HOSTCFLAGS=${HOSTCFLAGS:--Wall -Wstrict-prototypes -O2 -fomit-frame-pointer}
-
- if kernel_is 2 4; then
- yes "" | make oldconfig ${xmakeopts}
- einfo ">>> make oldconfig complete"
- make dep ${xmakeopts}
- elif kernel_is 2 6; then
- # 2.6.18 introduces headers_inst