krb5 does not build with musl anymore

[utdemir]

After #80599 (krb5: 1.17 -> 1.18) is merged, krb5 doesn't build with pkgsMusl anymore.

The error is:

...
gcc -fPIC -DSHARED -DHAVE_CONFIG_H  -I../../include -I../../include  -DKRB5_DEPRECATED=1 -DKRB5_PRIVATE  -g -O2 -Wall -Wcast-align -Wshadow -Wmissing-prototypes -Wno-format-zero-length -Woverflow -Wstrict-overflow -Wmissing-format-attribute -Wmissing-prototypes -Wreturn-type -Wmissing-braces -Wparentheses -Wswitch -Wunused-function -Wunused-label -Wunused-variable -Wunused-value -Wunknown-pragmas -Wsign-compare -Werror=uninitialized -Wno-maybe-uninitialized -Werror=pointer-arith -Werror=int-conversion -Werror=incompatible-pointer-types -Werror=discarded-qualifiers -Werror=implicit-int -Werror=declaration-after-statement -Werror-implicit-function-declaration -pthread  -c utf8.c -o utf8.so.o && mv -f utf8.so.o utf8.so
plugins.c:67:21: error: missing binary operator before token "("
   67 | #if ! __GLIBC_PREREQ(2, 25)
      |                     ^
make[1]: *** [Makefile:1095: plugins.so] Error 1
make[1]: *** Waiting for unfinished jobs....
fake-addrinfo.c: In function ‘my_fake_getaddrinfo’:
fake-addrinfo.c:1200:16: warning: variable ‘herr’ set but not used [-Wunused-but-set-variable]
 1200 |         int i, herr;
      |                ^~~~
make[1]: Leaving directory '/build/krb5-1.18/src/util/support'
make: *** [Makefile:888: all-recurse] Error 1
note: keeping build directory '/tmp/nix-build-libkrb5-1.18.drv-0'
builder for '/nix/store/bcn73i403brcnvhrpa2fgjn6nb2khzjb-libkrb5-1.18.drv' failed with exit code 2
error: build of '/nix/store/bcn73i403brcnvhrpa2fgjn6nb2khzjb-libkrb5-1.18.drv' failed

Since krb5 is a dependency of curl, this affects significant number of downstream packages.

To Reproduce

$ cd nixpkgs
$ git checkout 5d33637dd940f2053724359c207c052647ce7112
$ nix-build -A pkgsMusl.libkrb5 

cc @r-ryantm @vcunat @nh2