[MacPorts] #64011: ports that use use_xmkmf yes fail with make Makefiles failure

[MacPorts]

#64011: ports that use use_xmkmf yes fail with make Makefiles failure
------------------------+-----------------------------
 Reporter:  ryandesign  |      Owner:  ryandesign
     Type:  defect      |     Status:  assigned
 Priority:  Normal      |  Milestone:  MacPorts Future
Component:  base        |    Version:  2.7.1
 Keywords:              |       Port:
------------------------+-----------------------------
 Ports that use `use_xmkmf yes` fail to build. For example:

 {{{
 $ sudo port -n build tgif
 --->  Cleaning tgif
 --->  Computing dependencies for tgif
 --->  Fetching distfiles for tgif
 --->  Verifying checksums for tgif
 --->  Extracting tgif
 --->  Applying patches to tgif
 --->  Configuring tgif
 Error: Failed to configure tgif: make Makefiles failure: can't read "cd
 /opt/local/var/macports/build/_Users_rschmidt_macports_macports-ports-
 ryandesign-fork_graphics_tgif/tgif/work/tgif-QPL-4.2.5 && make
 Makefiles.dir": no such variable
 Error: See /opt/local/var/macports/logs/_Users_rschmidt_macports_macports-
 ports-ryandesign-fork_graphics_tgif/tgif/main.log for details.
 Error: Follow https://guide.macports.org/#project.tickets if you believe
 there is a bug.
 Error: Processing of port tgif failed
 }}}

 This has the same root cause as #63931: as of
 [da3524e8a3006a9b9a2370b66fa91bb554dd768b/macports-base] (which introduced
 build progress bars) which was included for the first time in MacPorts
 2.7.0, `command_exec` requires flags to be specified before the command
 but not all uses of `command_exec` were adjusted to match this new
 requirement; the invocation of `command_exec` for running `make Makefiles`
 when using xmkmf was not.

 In addition, `command_exec` no longer honors the `-varprefix` flag which
 `use_xmkmf yes` requires.

-- 
Ticket URL: <https://trac.macports.org/ticket/64011>
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