libxml2 compile error

libtool: compile:  /opt/sunstudio12.1/bin/cc -DHAVE_CONFIG_H -I. -I.. -I./include -I../include -D_REENTRANT -I/opt/local/zlib//include -g -c ../relaxng.c  -KPIC -DPIC -o .libs/relaxng.o
"../relaxng.c", line 5372: operands have incompatible types:
         pointer to char ":" pointer to const unsigned char
"../relaxng.c", line 5372: warning: argument #5 is incompatible with prototype:
        prototype: pointer to const unsigned char : "../relaxng.c", line 510
        argument : pointer to char
"../relaxng.c", line 9462: warning: argument #3 is incompatible with prototype:
        prototype: pointer to const unsigned char : "../relaxng.c", line 2347
        argument : pointer to char
cc: acomp failed for ../relaxng.c
*** Error code 1
make: Fatal error: Command failed for target `relaxng.lo'
Current working directory /export/home/user/Source/libxml2-2.7.6/.32.