Currently our CI machine on FreeBSD fails to build with the following
error message:
```
bytecomp/generate_runtimedef.sh runtime/caml/fail.h runtime/primitives > bytecomp/runtimedef.ml
/bin/sh: bytecomp/generate_runtimedef.sh: not found
```
This PR converts all the files with a `/bin/bash` shebang to
`/usr/bin/env bash`. Some files use `/bin/sh` instead, and they are
unchanged. It may be the case that some 'bash' files could in fact run
using 'sh', but checking this requires more work and I decided to
follow the original author's intent.
(Personally I like using bash explicitly as it gives a consistent
programming environment that I can easily test on my machine; but this
should not be at the expense of portability.)
In order to prepare the transition to autoconf, this commit moves the
configuration Makefile out of the config directory which will disappear
and gives it the name it will have once intstalled, namely Makefile.config.
This commit renames a few C compiler related build variables so that
they are reserved for the build system. They will then be re-introduced,
but this time as user varialbes whose value can be freely customized
when compiling the package, without risking to conflict with those
command-line flags that are required by the build system itself.
Here are the variables this commit renames:
- CFLAGS -> OC_CFLAGS
- CPPFLAGS -> OC_CPPFLAGS
- LDFLAGS -> OC_LDFLAGS
Note: before this commit the compilation of scheduler.c in
otherlibs/threads was relying on make's implicit rule to compile C files.
Since this commit stops using the standard variables for flags,
it is necessary to introduce an explicit rule to compile C files
and that makes use of the newly introduced variables.