[gimp] plug-ins: fix goat-invasion plug-ins installation.

[Jehan <jehanp src gnome org>]

commit 9e830c0c30bfa52e531d583e89b91ea8a1354405
Author: Jehan <jehan girinstud io>
Date:   Fri Oct 11 14:23:17 2019 +0200

    plug-ins: fix goat-invasion plug-ins installation.
    
    My commit c77c903c8d was obviously wrong since I realize that by fixing
    the C plug-in installation, I broke non-C goat-exercise plug-ins
    installation. This fixes it.

 plug-ins/goat-exercises/meson.build | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/plug-ins/goat-exercises/meson.build b/plug-ins/goat-exercises/meson.build
index c5ef220560..58e5996dd9 100644
--- a/plug-ins/goat-exercises/meson.build
+++ b/plug-ins/goat-exercises/meson.build
@@ -1,6 +1,6 @@
 # C version
 
-plugin_name = 'goat-exercise-c'
+plugin_name = 'goat-exercise'
 
 plugin_sources = [
   'goat-exercise-c.c',
@@ -10,7 +10,7 @@ if platform_windows
   plugin_sources += windows.compile_resources(
     gimp_plugins_rc,
     args: [
-      '--define', 'ORIGINALFILENAME_STR="@0@"'.format(plugin_name+'.exe'),
+      '--define', 'ORIGINALFILENAME_STR="@0@"'.format(plugin_name + '-c.exe'),
       '--define', 'INTERNALNAME_STR="@0@"'    .format(plugin_name),
       '--define', 'TOP_SRCDIR="@0@"'          .format(meson.source_root()),
     ],
@@ -20,7 +20,7 @@ if platform_windows
   )
 endif
 
-executable(plugin_name,
+executable(plugin_name + '-c',
   plugin_sources,
   include_directories: [ rootInclude, ],
   dependencies: [
@@ -36,7 +36,7 @@ executable(plugin_name,
     libgimpwidgets,
   ],
   install: true,
-  install_dir: gimpplugindir /  'plug-ins' / plugin_name,
+  install_dir: gimpplugindir /  'plug-ins' / plugin_name + '-c',
 )
 
 install_data(