This patch adds some checks on the external toolchains.
First, it checks that the C library selection is correct, by looking
if gcc is able to find the main C library file through the
-print-file-name option.
Then, it attempts to check if the Buildroot toolchain options match
the configuration of the toolchain :
* for glibc, it checks that IPv6, RPC, locales, wide-char, large file
support Buildroot options are enabled, since with glibc all these
features are always available (at least this is the assumption we
make) ;
* for uClibc, it checks the Buildroot options with the uClibc
configuration file in $SYSROOT_DIR/usr/include/bits/uClibc_config.h
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
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