[BUILD] Premake: do not add target suffix to OSX anymore, even on gmake

[CI] Travis: adapted build paths since OSX gmake builds .app like Xcode

.travis.yml

@@ -38,7 +38,7 @@ jobs:
         - PREMAKE_GENERATOR=gmake
         # There are two OSX builds deployed, here is the gmake build
         - DEPLOY=true
-        - DEPLOY_FILE=build/macosx_gmake_Release/bin/Game_OSX.zip
+        - DEPLOY_FILE=build/macosx_gmake_Release/bin/Game_gmake.app.zip
       compiler: clang++
     - os: osx
       osx_image: xcode11.6
@@ -174,7 +174,7 @@ before_deploy:
     elif [[ $TRAVIS_OS_NAME == "osx" ]]; then
       if [[ $PREMAKE_GENERATOR == "gmake"* ]]; then
         pushd build/macosx_${PREMAKE_GENERATOR}_Release/bin
-        zip -r Game_OSX.zip Game_OSX
+        zip -r Game_gmake.app.zip Game.app
         popd
       else
         pushd build/macosx_${PREMAKE_GENERATOR}_Release/bin

premake5.lua

@@ -50,8 +50,7 @@ project "Game"
         frameworkdirs {"engine/third-party/SFML/extlibs/libs-osx/Frameworks"}
 
     filter { "system:macosx", "action:gmake*"}
-        -- both OSX and Linux can generate extensionless executables, so add a suffix to distinguish them
-        targetsuffix "_OSX"
+        -- it seems that even with gmake, OSX builds an .app, so no need to add target suffix "_OSX"
 
         -- unlike ...dirs {}, linkoptions does not interpret paths
         -- so we must enter them relatively to location "build", hence "../"
@@ -75,7 +74,8 @@ project "Game"
         }
 
     filter { "system:linux" }
-        -- both OSX and Linux can generate extensionless executables, so add a suffix to distinguish them
+        -- only Linux can generate extensionless executables, but we keep the target suffix
+        -- we prepared when we thought OSX gmake would also build one, for now
         targetsuffix "_Linux"
 
         -- on Linux, we basically use the list on https://www.sfml-dev.org/tutorials/2.5/compile-with-cmake.php