Experimental approach to tackle the problem with Be's negative error codes and

ported software:
* If the macro B_USE_POSITIVE_POSIX_ERRORS is defined the POSIX error code
  constants (ENOMEM, EINTR,...) will have positive values.
* Introduced the macros B_TO_{POSITIVE,NEGATIVE}_ERROR() which do convert a
  given error code to a positive/negative value.
* Added static library libposix_error_mapper.a that overrides all POSIX
  functions (save the ones I forgot to add :-)) directly meddling with error
  codes (having them as parameter or returning them) dealing with the
  positive<->negative error code conversions. The functions have hidden
  visibility, so they affect only the shared object they are linked into.
* So ideally all one has to do is to build a ported software with
  -DB_USE_POSITIVE_POSIX_ERRORS and -lposix_error_mapper and be good with
  respect to error code problems.
* Potential issues:
  - When mixing ported and Haiku native code, i.e. using Haiku native code in
    a ported software or using a ported library in a Haiku native application
    care must be taken to convert error codes where the two interface. That's
    what the B_TO_{POSITIVE,NEGATIVE}_ERROR() macros are supposed to be used
    for.
  - A ported static library can obviously not be linked directly against
    -lposix_error_mapper. The shared object linking a against the ported static
    library has to do that. The previous point applies when that causes mixing
    with Haiku native code.
  - When dependent ported libraries are used probably all of them should use
    the error mapping.

Comments welcome.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@29653 a95241bf-73f2-0310-859d-f6bbb57e9c96

build/jam/OptionalPackages

@@ -194,6 +194,9 @@ if [ IsOptionalHaikuImagePackageAdded Development ] && $(TARGET_ARCH) = x86 {
 	# static libraries
 	AddFilesToHaikuImage develop lib x86 : libncurses.a ;
 
+	# the POSIX error code mapper library
+	AddFilesToHaikuImage develop lib x86 : libposix_error_mapper.a ;
+
 	# cc and c++ wrapper scripts
 	AddFilesToHaikuImage beos bin : cc c++ ;