Introduce the SR_CHECK_COMPILE_FLAGS macro and use it to check
for additional compiler flags. Put the accepted flags into the
separate substitution variable SR_EXTRA_CFLAGS.
With this and the preceding changes, bug #578 should now be fixed.
Use the SR_ARG_ENABLE_WARNINGS macro to configure and check for
the availability of compiler warning flags. Maintain separate
sets of warning flags for C and C++.
The configure option --enable-warnings=[min|max|fatal|no] can
be used to set the compiler warning level for all languages.
The default level is "max".
Place custom Autoconf macros which other sigrok modules may
re-use into a separate file m4/sigrok.m4. Also, introduce new
macros for defining the package and library versions, and for
gathering compiler warning flags.
Daniel Elstner