Merge pull request #9834 from Harry-Ramsey/fix-submodule-error-messages-3.6

[Backport 3.6] Fix submodule error messages
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b0a6a6a..99e2169 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -315,7 +315,7 @@
 endif()
 
 if (NOT EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/framework/CMakeLists.txt")
-    if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/.git/")
+    if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/.git")
         message(FATAL_ERROR "${CMAKE_CURRENT_SOURCE_DIR}CMakeLists.txt not found (and does appear to be a git checkout). Run `git submodule update --init` from the source tree to fetch the submodule contents.")
     else ()
         message(FATAL_ERROR "${CMAKE_CURRENT_SOURCE_DIR}/CMakeLists.txt not found (and does not appear to be a git checkout). Please ensure you have downloaded the right archive from the release page on GitHub.")
diff --git a/Makefile b/Makefile
index 1b21369..e0edde4 100644
--- a/Makefile
+++ b/Makefile
@@ -6,7 +6,7 @@
     ifeq (,$(wildcard framework/exported.make))
         # Use the define keyword to get a multi-line message.
         # GNU make appends ".  Stop.", so tweak the ending of our message accordingly.
-        ifeq (,$(wildcard .git))
+        ifneq (,$(wildcard .git))
             define error_message
 ${MBEDTLS_PATH}/framework/exported.make not found (and does appear to be a git checkout). Run `git submodule update --init` from the source tree to fetch the submodule contents.
 This is a fatal error