Merge branch 'js/azure-pipelines-msvc'

CI updates.

* js/azure-pipelines-msvc:
  ci: also build and test with MS Visual Studio on Azure Pipelines
  ci: really use shallow clones on Azure Pipelines
  tests: let --immediate and --write-junit-xml play well together
  test-tool run-command: learn to run (parts of) the testsuite
  vcxproj: include more generated files
  vcxproj: only copy `git-remote-http.exe` once it was built
  msvc: work around a bug in GetEnvironmentVariable()
  msvc: handle DEVELOPER=1
  msvc: ignore some libraries when linking
  compat/win32/path-utils.h: add #include guards
  winansi: use FLEX_ARRAY to avoid compiler warning
  msvc: avoid using minus operator on unsigned types
  push: do not pretend to return `int` from `die_push_simple()`

compat/win32/path-utils.h

@@ -1,3 +1,6 @@
+#ifndef WIN32_PATH_UTILS_H
+#define WIN32_PATH_UTILS_H
+
 #define has_dos_drive_prefix(path) \
 	(isalpha(*(path)) && (path)[1] == ':' ? 2 : 0)
 int win32_skip_dos_drive_prefix(char **path);
@@ -18,3 +21,5 @@ static inline char *win32_find_last_dir_sep(const char *path)
 #define find_last_dir_sep win32_find_last_dir_sep
 int win32_offset_1st_component(const char *path);
 #define offset_1st_component win32_offset_1st_component
+
+#endif