Add new MSVC_LIB_PATH runtest environment variable to know location of the msvc_lib binary

Author: GuillaumeGomez

src/tools/compiletest/src/runtest.rs

@@ -3382,6 +3382,7 @@ impl<'test> TestCx<'test> {
             cmd.env("IS_MSVC", "1")
                 .env("IS_WINDOWS", "1")
                 .env("MSVC_LIB", format!("'{}' -nologo", lib.display()))
+                .env("MSVC_LIB_PATH", format!("{}", lib.display()))
                 .env("CC", format!("'{}' {}", self.config.cc, cflags))
                 .env("CXX", format!("'{}' {}", &self.config.cxx, cxxflags));
         } else {
@@ -3752,6 +3753,7 @@ impl<'test> TestCx<'test> {
             cmd.env("IS_MSVC", "1")
                 .env("IS_WINDOWS", "1")
                 .env("MSVC_LIB", format!("'{}' -nologo", lib.display()))
+                .env("MSVC_LIB_PATH", format!("{}", lib.display()))
                 // Note: we diverge from legacy run_make and don't lump `CC` the compiler and
                 // default flags together.
                 .env("CC_DEFAULT_FLAGS", &cflags)