Starting from commit f1350977634f ("package/fakeroot: bump to version 1.32.1"), see [1], Buildroot fails to compile early that way:
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libtool: compile:  /usr/bin/gcc -std=gnu11 -DHAVE_CONFIG_H -I. -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 -I.../buildroot/fakeroot/output/host/include -O2 -I.../buildroot/fakeroot/output/host/include -c libfakeroot_time64.c  -fPIC -DPIC -o .libs/libfakeroot_time64_la-libfakeroot_time64.o
In file included from libfakeroot_time64.c:13:0:
/usr/include/fts.h:41:3: error: #error "<fts.h> cannot be used with -D_FILE_OFFSET_BITS==64"
 # error "<fts.h> cannot be used with -D_FILE_OFFSET_BITS==64"
   ^
make[3]: *** [libfakeroot_time64_la-libfakeroot_time64.lo] Error 1
make[3]: Leaving directory `.../buildroot/fakeroot/output/build/host-fakeroot-1.32.1'
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory `.../buildroot/fakeroot/output/build/host-fakeroot-1.32.1'
make[1]: *** [all] Error 2
make[1]: Leaving directory `.../buildroot/fakeroot/output/build/host-fakeroot-1.32.1'
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That happens due to a change in the fakeroot, see [2].
It boils down to use of "fts.h" on 64-bit system with old glibc.
I.e. support of "fts.h" was added in glibc 2.23, see [3]. And in its turn CentOS 7.x uses glibc 2.17, thus we see this (shamelessly copied from [4]):
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> cat test.c
#include <fts.h>

int main() {
}

> cc -D_FILE_OFFSET_BITS=64 test.c
In file included from test.c:1:0:
/usr/include/fts.h:41:3: error: #error "<fts.h> cannot be used with -D_FILE_OFFSET_BITS==64"
 # error "<fts.h> cannot be used with -D_FILE_OFFSET_BITS==64"
#include <fts.h>

int main() {
}
----------------------->8-----------------------

Note, with older fakeroot, i.e. reverted [1] my simple build gets to the end successfully.

[1] https://git.buildroot.net/buildroot/commit/?h=f1350977634f96f0404b9801e6f79cb7200cf26d
[2] https://salsa.debian.org/clint/fakeroot/-/commit/c465f716856cd561dba3522a4f5c714ea8bedfbd
[3] https://sourceware.org/git/?p=glibc.git;a=commit;h=8b7b7f75d91f7bac323dd6a370aeb3e9c5c4a7d5
[4] https://github.com/mesonbuild/meson/issues/3519#issuecomment-386281558