Clang error on AIX

Hi there-
   Using the IBM clang-based Open XL C 17.1.0, I'm getting the following sequence of errors when trying to compile src/rx/AIX/rx_knet.c:

/home/build/openafs/src/rx/AIX/rx_knet.c:378:6: error: expected expression
            MGETHDR(m, M_DONTWAIT, MT_DATA);
            ^
../sys/mbuf_macro.h:389:25: note: expanded from macro 'MGETHDR'
        (m)->m_eyecat = EYEC_MBUFA;                                             \
                        ^
../sys/mbuf_base.h:79:61: note: expanded from macro 'EYEC_MBUFA'
#define EYEC_MBUFA      __EYEC8('m','b','u','f','A','L','L','')/* %mbufALL */
                                                            ^

   And a few others that are similar, all going back to the EYEC_MBUFA definition.  The ^ is under the '' in case the font doesn't display this message correctly.   What exactly is this telling me, and any suggestions on how to resolve?  sys/mbuf_base.h is a system header and we can't exactly change it...

Thank you for any tips!

-Ben