- fix build error reported by buildbot by disabling krb5
- libcom_err from krb5 is used - configure output:
configure: WARNING: library 'com_err' is required for Heimdal Kerberos
- krb5 has its own libcom_err (see krb5 package) with its own symbols

- linking with wrong libcom_err from libext2fs produces errors during
libgssapi_krb5.so: undefined reference to `error_message@com_err_3_MIT'
libgssapi_krb5.so: undefined reference to `remove_error_table@com_err_3_MIT'
libgssapi_krb5.so: undefined reference to `add_error_table@com_err_3_MIT'
-> remove libext2fs dependency (wasnt working anyway - no PKG_BUILD_DEP)

Signed-off-by: Dirk Neukirchen <dirkneukirchen@web.de>

squid uses libcom_err, a static library provided by libext2fs

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

Signed-off-by: Marko Ratkaj <marko.ratkaj@sartura.hr>

Signed-off-by: Daniel Gimpelevich <daniel@gimpelevich.san-francisco.ca.us>

Signed-off-by: Luka Perkov <luka@openwrt.org>

Signed-off-by: Marko Ratkaj <marko.ratkaj@sartura.hr>

Change `sys/signal.h` include to just `signal.h`. The build otherwise fails
due to `-Werror` with the following message:

    In file included from rfcnb-io.c:43:0:
    .../staging_dir/toolchain-mipsel_mips32_gcc-4.8-linaro_musl-1.1.10/include/sys/signal.h:1:2: error: #warning redirecting incorrect #include <sys/signal.h> to <signal.h> [-Werror=cpp]
     #warning redirecting incorrect #include <sys/signal.h> to <signal.h>
      ^
    cc1: all warnings being treated as errors

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

Signed-off-by: Marko Ratkaj <marko.ratkaj@sartura.hr>

Signed-off-by: Luka Perkov <luka@openwrt.org>

Signed-off-by: Marko Ratkaj <marko.ratkaj@sartura.hr>

Signed-off-by: Nicolas Thill <nico@openwrt.org>

Signed-off-by: Marko Ratkaj <marko.ratkaj@sartura.hr>

Signed-off-by: Luka Perkov <luka@openwrt.org>