Using the just released 3.4.0pre2:

The host build of heimdal fails when building with a glibc gcc as the hostcc and a uclibc gcc as the targetcc with:

Linking bin/asn1_compile
bin/mergedobj/replace_hostcc.o: In function `rep_mkstemp':
(.text+0x12): warning: the use of `mktemp' is dangerous, better use `mkstemp' or `mkdtemp'
bin/mergedobj/heimdal_roken_h.o: In function `print_arg':
getarg.c:(.text+0x7bd): undefined reference to `strlcat'
getarg.c:(.text+0x7d7): undefined reference to `strlcat'
getarg.c:(.text+0x7f9): undefined reference to `strlcat'
getarg.c:(.text+0x815): undefined reference to `strlcat'
getarg.c:(.text+0x8ac): undefined reference to `strlcat'
bin/mergedobj/heimdal_roken_h.o: In function `mandoc_template':
getarg.c:(.text+0x99e): undefined reference to `strlcpy'
bin/mergedobj/heimdal_roken_h.o: In function `arg_printusage_i18n':
(.text+0x1197): undefined reference to `strlcpy'
bin/mergedobj/heimdal_roken_h.o: In function `arg_printusage_i18n':
(.text+0x11d7): undefined reference to `strlcat'
bin/mergedobj/heimdal_roken_h.o: In function `arg_printusage_i18n':
(.text+0x1210): undefined reference to `strlcat'
bin/mergedobj/heimdal_roken_h.o: In function `arg_printusage_i18n':
(.text+0x12ba): undefined reference to `strlcat'
bin/mergedobj/heimdal_roken_h.o: In function `arg_printusage_i18n':
(.text+0x12f3): undefined reference to `strlcat'
bin/mergedobj/heimdal_roken_h.o: In function `arg_printusage_i18n':
(.text+0x1322): undefined reference to `strlcat'
bin/mergedobj/heimdal_roken_h.o:(.text+0x13c6): more undefined references to `strlcat' follow
bin/mergedobj/heimdal_roken_h.o: In function `parse_record':
resolve.c:(.text+0x3326): undefined reference to `__dn_expand'
resolve.c:(.text+0x34f6): undefined reference to `__dn_expand'
resolve.c:(.text+0x3585): undefined reference to `__dn_expand'
resolve.c:(.text+0x3661): undefined reference to `strlcpy'
resolve.c:(.text+0x3694): undefined reference to `__dn_expand'
resolve.c:(.text+0x37c0): undefined reference to `strlcpy'
resolve.c:(.text+0x39a7): undefined reference to `__dn_expand'
resolve.c:(.text+0x3c0e): undefined reference to `strlcpy'
bin/mergedobj/heimdal_roken_h.o: In function `parse_reply':
resolve.c:(.text+0x41b7): undefined reference to `__dn_expand'
bin/mergedobj/heimdal_roken_h.o: In function `dns_lookup_int':
resolve.c:(.text+0x44e3): undefined reference to `__res_search'
collect2: ld returned 1 exit status
make[3]: *** [bin/asn1_compile] Error 1

The problem seems to be that all availability tests for functions are only done for the target, but not for the host.