Add link=shared configurations to Appveyor

appveyor.yml

@@ -1,4 +1,4 @@
-# Copyright 2016-2019 Peter Dimov
+# Copyright 2016-2020 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)
 
@@ -31,6 +31,35 @@ environment:
     UBP: 1
     TOOLSET: msvc-14.1
     STAGE: 1
+  - LIB: filesystem
+    UBP: 1
+    LINK: shared
+    TOOLSET: msvc-14.1
+  - LIB: filesystem
+    UBP: 1
+    LINK: static,shared
+    TOOLSET: msvc-14.1
+  - LIB: filesystem
+    UBP: 1
+    LINK: static,shared
+    USE_STATIC_LIBS: OFF
+    TOOLSET: msvc-14.1
+  - LIB: filesystem
+    UBP: 1
+    STAGE: 1
+    LINK: shared
+    TOOLSET: msvc-14.1
+  - LIB: filesystem
+    UBP: 1
+    STAGE: 1
+    LINK: static,shared
+    TOOLSET: msvc-14.1
+  - LIB: filesystem
+    UBP: 1
+    STAGE: 1
+    LINK: static,shared
+    USE_STATIC_LIBS: OFF
+    TOOLSET: msvc-14.1
   - LIB: headers
     TOOLSET: msvc-14.1
   - LIB: iostreams
@@ -91,11 +120,12 @@ test_script:
   - if not "%LAYOUT%" == "" SET LAYOUT=--layout=%LAYOUT%
   - if not "%TOOLSET%" == "" SET TOOLSET=toolset=%TOOLSET%
   - if not "%PYTHON%" == "" SET PYTHON=python=%PYTHON%
+  - if not "%LINK%" == "" SET LINK=link=%LINK%
   - set ZLIB_SOURCE=%CD%\tools\boost_install\test\iostreams\zlib-1.2.11
   - set BZIP2_SOURCE=%CD%\tools\boost_install\test\iostreams\bzip2-1.0.8
   - if "%STAGE%" == "" set B2_INSTALL=--prefix=C:\projects\.local install
-  - if "%STAGE%" == "" b2 -j3 -d0 --with-headers %TOOLSET% %LAYOUT% %PYTHON% %B2_INSTALL%
-  - b2 -j3 --with-%LIB% %TOOLSET% %LAYOUT% %PYTHON% %B2_INSTALL%
+  - if "%STAGE%" == "" b2 -j3 -d0 --with-headers %TOOLSET% %LAYOUT% %PYTHON% %LINK% %B2_INSTALL%
+  - b2 -j3 --with-%LIB% %TOOLSET% %LAYOUT% %PYTHON% %LINK% %B2_INSTALL%
   - cd tools\boost_install\test\%LIB%
   - mkdir __build__ && cd __build__
   - if "%UBP%" == "" SET UBP=0