CMake: ensure static libraries are still installed on Emscripten (#988)

Similar to commit ce222e317e36aa362e83fc50c7a6226d238e03fd.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7ee3973..d8a956d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -217,14 +217,12 @@
     RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
   )
 
-  if(NOT BROTLI_EMSCRIPTEN)
-    install(
-      TARGETS ${BROTLI_LIBRARIES_CORE}
-      ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
-      LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
-      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
-    )
-  endif()  # BROTLI_EMSCRIPTEN
+  install(
+    TARGETS ${BROTLI_LIBRARIES_CORE}
+    ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+    LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+  )
 
   install(
     DIRECTORY ${BROTLI_INCLUDE_DIRS}/brotli