Either upgrade Autoconf, or use AC_PROG_CC_C99 instead of AC_PROG_CC
The release tarballs contain configure scripts generated with Autoconf 2.69
.
They do not check whether the compiler supports C99, but the project is written in C99.
Please either upgrade Autoconf to 2.70, where AC_PROG_CC
checks for support of C99:
If
ac_cv_prog_cc_c11
is set to any value other than ‘no’ (including the empty string), then CC can compile code as standard C 2011, and this mode has been enabled. Otherwise, ifac_cv_prog_cc_c99
is set to any value other than ‘no’ (including the empty string), then CC can compile code as standard C 1999, and this mode has been enabled.
Or stick to Autoconf 2.69 but use the (now obsolete) macro AC_PROG_CC_C99
:
https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/C-Compiler.html
— Macro: AC_PROG_CC_STDC
If the C compiler cannot compile ISO Standard C (currently C99), try to add an option to output variable CC to make it work. If the compiler does not support C99, fall back to supporting ANSI C89 (ISO C90). After calling this macro you can check whether the C compiler has been set to accept Standard C; if not, the shell variable ac_cv_prog_cc_stdc is set to ‘no’.