A few approaches to simulate alignof are documented here:

http://www.m17n.org/martin/writings/alignof.html

The following macro would work for fontconfig's uses, and would also go toward
fixing bug 6099.

#define fc_alignof(type) offsetof (struct { char c; type member; }, member)

Patch forthcoming.

Created attachment 5219 [details] [review]
patch to implement __alignof__ portably

First problem: fcint.h uses HAVE_INTTYPES_H before config.h is included.

HP-UX doesn't understand __inline__ to :-(
So I set CFLAGS to -D__inline__=

cc: "fcint.h", line 486: error 1000: Unexpected symbol: "int".
cc: "fcint.h", line 626: error 1000: Unexpected symbol: "int".
cc: "fcint.h", line 626: error 1586: Redefinition of function "__inline__".
cc: "fcint.h", line 626: error 1711: Inconsistent parameter list declaration 
for "__inline__".
cc: "fcint.h", line 833: error 1000: Unexpected symbol: "int".
cc: "fcint.h", line 833: error 1586: Redefinition of function "__inline__".
cc: "fcint.h", line 833: error 1711: Inconsistent parameter list declaration 
for "__inline__".
cc: "fcint.h", line 901: error 1000: Unexpected symbol: "FcValueList".
cc: "fcint.h", line 905: warning 604: Pointers are not assignment-compatible.
cc: "fcint.h", line 907: warning 604: Pointers are not assignment-compatible.
cc: "fcint.h", line 910: error 1000: Unexpected symbol: "FcPatternElt".
cc: "fcint.h", line 914: warning 604: Pointers are not assignment-compatible.
cc: "fcint.h", line 916: warning 604: Pointers are not assignment-compatible.

in fcint.h is a macro ALIGN. It has to be fixed, too.

Created attachment 5222 [details] [review]
missed 2 __alignof__ in fcint.h

This catches another __alignof__ use in fcint.h.

There is a patch in bug 6171 to handle the stdint/inttypes problem.

Created attachment 5223 [details] [review]
patch to check for 'inline' in configure.in

Uses AC_C_INLINE, which should expand to inline/__inline__/__inline/nothing as
appropriate.

I've committed these patches.  Please REOPEN if it doesn't work.

config.h includes now a definition for inline:

/* Define to `__inline__' or `__inline' if that's what the C compiler
   calls it, or to nothing if 'inline' is not supported under any name.  */
#ifndef __cplusplus
#define inline __inline
#endif

But now I get this error

cc  -O -Ae +DAportable  -Wl,+vshlibunsats -Wl,-z -Wl,+s -Wl,-B,immediate -o
fc-case  fc-case.o  
/usr/ccs/bin/ld: Unsatisfied symbols:
   _fcValueLists (first referenced in fc-case.o) (data)
   _fcPatternElts (first referenced in fc-case.o) (data)
   FcDebugVal (first referenced in fc-case.o) (data)

Should I make a new bug report or reopen this one?

BTW, many thanks Dom & Patrick for your support so far.

New bug report, please. Thanks.