ci: don't do negotiate tests on windows

We can't get a kerberos TGT easily on Windows; skip the negotiate tests.

azure-pipelines.yml

@@ -97,7 +97,7 @@ jobs:
         CMAKE_GENERATOR: Visual Studio 12 2013 Win64
         CMAKE_OPTIONS: -DMSVC_CRTDBG=ON -DDEPRECATE_HARD=ON
         SKIP_SSH_TESTS: true
-        GITTEST_NEGOTIATE_PASSWORD: $(GITTEST_NEGOTIATE_PASSWORD)
+        SKIP_NEGOTIATE_TESTS: true
 
 - job: windows_vs_x86
   displayName: 'Windows (x86; Visual Studio)'
@@ -109,7 +109,7 @@ jobs:
         CMAKE_GENERATOR: Visual Studio 12 2013
         CMAKE_OPTIONS: -DMSVC_CRTDBG=ON -DDEPRECATE_HARD=ON -DUSE_SHA1=HTTPS
         SKIP_SSH_TESTS: true
-        GITTEST_NEGOTIATE_PASSWORD: $(GITTEST_NEGOTIATE_PASSWORD)
+        SKIP_NEGOTIATE_TESTS: true
 
 - job: windows_mingw_amd64
   displayName: 'Windows (amd64; MinGW)'
@@ -127,7 +127,7 @@ jobs:
         CMAKE_GENERATOR: MinGW Makefiles
         CMAKE_OPTIONS: -DDEPRECATE_HARD=ON
         SKIP_SSH_TESTS: true
-        GITTEST_NEGOTIATE_PASSWORD: $(GITTEST_NEGOTIATE_PASSWORD)
+        SKIP_NEGOTIATE_TESTS: true
 
 - job: windows_mingw_x86
   displayName: 'Windows (x86; MinGW)'
@@ -146,7 +146,7 @@ jobs:
         CMAKE_GENERATOR: MinGW Makefiles
         CMAKE_OPTIONS: -DDEPRECATE_HARD=ON
         SKIP_SSH_TESTS: true
-        GITTEST_NEGOTIATE_PASSWORD: $(GITTEST_NEGOTIATE_PASSWORD)
+        SKIP_NEGOTIATE_TESTS: true
 
 - job: documentation
   displayName: 'Generate Documentation'