CI/azure: improve on flakiness by avoiding libtool wrappers

Install curl binaries into MinGW bin folder and use that
for the tests in order to avoid libtool wrapper binaries.

The libtool wrapper binaries (not scripts) on Windows seem
to be one of the possible causes for the following issues:

1. Process output can be lost in the wrapper process chain.
2. Killing the wrapper process does not kill the actual one.

Derived from curl#5904
Closes curl#6049

.azure-pipelines.yml

@@ -83,7 +83,7 @@ stages:
       displayName: 'configure $(name)'
 
     - script: make
-      displayName: 'make'
+      displayName: 'make && cd tests && make'
 
     - script: make test-nonflaky
       displayName: 'test'
@@ -188,11 +188,14 @@ stages:
     - script: $(container_cmd) -l -c "cd $(echo '%cd%') && ./buildconf && ./configure $(configure)"
       displayName: 'configure $(name)'
 
-    - script: $(container_cmd) -l -c "cd $(echo '%cd%') && make"
+    - script: $(container_cmd) -l -c "cd $(echo '%cd%') && make && cd tests && make"
       displayName: 'make'
 
+    - script: $(container_cmd) -l -c "cd $(echo '%cd%') && make install && PATH=/usr/bin:/bin find . -type f -path '*/.libs/*.exe' -print -execdir mv -t .. {} \;"
+      displayName: 'install'
+
     - script: $(container_cmd) -l -c "cd $(echo '%cd%') && make test-nonflaky"
       displayName: 'test'
       env:
         AZURE_ACCESS_TOKEN: "$(System.AccessToken)"
-        TFLAGS: "-r $(tests)"
+        TFLAGS: "-vc /usr/bin/curl.exe -r $(tests)"