drac ftbfs in groovy

[Matthias Klose]

seen in a groovy test rebuild:
https://launchpad.net/ubuntu/+archive/test-rebuild-20200925-groovy/+build/19982693

# Add here commands to compile the package.
/usr/bin/make all
make[1]: Entering directory '/<<PKGBUILDDIR>>'
gcc -DSOCK_RPC -DFCNTL_LOCK -DGETHOST -DDASH_C -g -O2 -fPIC -Wdate-time -D_FORTIFY_SOURCE=2 -c -o testing.o testing.c
testing.c:10:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
   10 | main(argc, argv)
      | ^~~~
testing.c: In function ‘main’:
testing.c:21:3: warning: implicit declaration of function ‘exit’ [-Wimplicit-function-declaration]
   21 | exit(1);
      | ^~~~
testing.c:21:3: warning: incompatible implicit declaration of built-in function ‘exit’
testing.c:9:1: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
    8 | #include <arpa/inet.h>
  +++ |+#include <stdlib.h>
    9 |
testing.c:25:7: warning: implicit declaration of function ‘dracauth’ [-Wimplicit-function-declaration]
   25 | rc = dracauth(host, ip, &err);
      | ^~~~~~~~
rpcgen -C -I drac.x
gcc -DSOCK_RPC -DFCNTL_LOCK -DGETHOST -DDASH_C -g -O2 -fPIC -Wdate-time -D_FORTIFY_SOURCE=2 -c -o dracauth.o dracauth.c
In file included from dracauth.c:21:
drac.h:9:10: fatal error: rpc/rpc.h: No such file or directory
    9 | #include <rpc/rpc.h>
      | ^~~~~~~~~~~
compilation terminated.
make[1]: *** [<builtin>: dracauth.o] Error 1
make[1]: Leaving directory '/<<PKGBUILDDIR>>'
make: *** [debian/rules:23: build-stamp] Error 2