Simplify autoconf checking

Fold some checks already implicit in the libtool one and require C99
instead of checking for standard headers and libraries

configure.ac

@@ -29,37 +29,13 @@ AM_CONDITIONAL(ARMV7NEON, test x$armv7neon = xyes)
 
 # Checks for programs.
 AM_PROG_AS
-AC_PROG_CC
+AC_PROG_CC_C99
 AC_PROG_CXX
-AC_PROG_INSTALL
-AC_PROG_LN_S
-AC_PROG_MAKE_SET
 
 # Setup for libtool
 AC_PROG_LIBTOOL
 AC_SUBST(LIBTOOL_DEPS)
 
-# Checks for libraries.
-AC_CHECK_LIB([], [main])
-
-# Checks for header files.
-AC_CHECK_HEADERS([stdint.h stdlib.h string.h])
-
-# Checks for typedefs, structures, and compiler characteristics.
-AC_C_INLINE
-AC_TYPE_INT16_T
-AC_TYPE_INT32_T
-AC_TYPE_INT64_T
-AC_TYPE_INT8_T
-AC_TYPE_UINT16_T
-AC_TYPE_UINT32_T
-AC_TYPE_UINT64_T
-AC_TYPE_UINT8_T
-
-# Checks for library functions.
-AC_FUNC_MALLOC
-AC_CHECK_FUNCS([memset])
-
 # soname version to use
 # goes by ‘current[:revision[:age]]’ with the soname ending up as
 # current.age.revision.