Update Make.config

- branch name was still pointing to `xcode9`, not `master`

- version was 11.5, half true since we need to re-branch 15.5 (11.4), so down to 11.3 to be temporarily correct

- remove useless comment about xcode version, both the path and download link include the version

Make.config

@@ -31,7 +31,7 @@ PACKAGE_HEAD_REV=$(shell git rev-parse HEAD)
 # on wrench, because wrench technically builds hashes, not branches)
 #
 # 
-PACKAGE_HEAD_BRANCH=xcode9
+PACKAGE_HEAD_BRANCH=master
 ifeq ($(BUILD_REVISION),)
 CURRENT_BRANCH:=$(shell git rev-parse --abbrev-ref HEAD)
 else
@@ -45,14 +45,13 @@ IOS_PRODUCT=Xamarin.iOS
 IOS_PACKAGE_NAME=Xamarin.iOS
 IOS_PACKAGE_NAME_LOWER=$(shell echo $(IOS_PACKAGE_NAME) | tr "[:upper:]" "[:lower:]")
 # NEVER customize IOS_PACKAGE_VERSION itself, other parts (mtouch, web updater) are using the IOS_PACKAGE_VERSION_* variables
-IOS_PACKAGE_VERSION=11.5.$(PACKAGE_VERSION_REV).$(IOS_COMMIT_DISTANCE)
+IOS_PACKAGE_VERSION=11.3.$(PACKAGE_VERSION_REV).$(IOS_COMMIT_DISTANCE)
 IOS_PACKAGE_VERSION_MAJOR=$(word 1, $(subst ., ,$(IOS_PACKAGE_VERSION)))
 IOS_PACKAGE_VERSION_MINOR=$(word 2, $(subst ., ,$(IOS_PACKAGE_VERSION)))
 IOS_PACKAGE_VERSION_REV=$(PACKAGE_VERSION_REV)
 IOS_PACKAGE_VERSION_BUILD=$(IOS_COMMIT_DISTANCE)
 IOS_PACKAGE_UPDATE_ID=$(shell printf "2%02d%02d%02d%03d" $(IOS_PACKAGE_VERSION_MAJOR) $(IOS_PACKAGE_VERSION_MINOR) $(IOS_PACKAGE_VERSION_REV) $(IOS_PACKAGE_VERSION_BUILD))
 
-# Xcode 9 beta 6
 XCODE_VERSION=9
 XCODE_URL=http://xamarin-storage/bot-provisioning/Xcode_9_GM_seed.xip
 XCODE_DEVELOPER_ROOT=/Applications/Xcode9-GM.app/Contents/Developer