This was needed afterall. Without this Apache segfaulted when accessing PHP scripts.

TSRM/tsrm_config_common.h

@@ -16,8 +16,19 @@
 #include <malloc.h>
 #endif
 
-#if HAVE_ALLOCA_H
-#include <alloca.h>
+/* AIX requires this to be the first thing in the file.  */
+#ifndef __GNUC__
+# if HAVE_ALLOCA_H
+#  include <alloca.h>
+# else
+#  ifdef _AIX
+ #pragma alloca
+#  else
+#   ifndef alloca /* predefined by HP cc +Olibcalls */
+char *alloca ();
+#   endif
+#  endif
+# endif
 #endif
 
 #if HAVE_UNISTD_H