postgresql-7.1.3 bugs

make -C ../../../src/interfaces/libpq all
make[1]: Entering directory
`/usr/local/src/postgresql-7.1.3/src/interfaces/libpq'
make[1]: Nothing to be done for `all'.
make[1]: Leaving directory
`/usr/local/src/postgresql-7.1.3/src/interfaces/libpq'
gcc -O2 -Wall -Wmissing-prototypes -Wmissing-declarations
pg_encoding.o -L../../
../src/interfaces/libpq -lpq -Wl,-rpath,/usr/local/pgsql/lib -lcrypt -lreso
lv -lnsl -ldl -lm -o pg_encoding
pg_encoding.o: In function `main':
pg_encoding.o(.text+0x3d): undefined reference to `pg_char_to_encoding'
pg_encoding.o(.text+0x81): undefined reference to `pg_encoding_to_char'
collect2: ld returned 1 exit status
make: *** [pg_encoding] Error 1

Why???