make host pico_platform.h and binary_info.h CMakeLists.txt safe for inclusion in non SDK build (#388)

* make host pico_platform.h and binary_info.h CMakeLists.txt safe for inclusion in non SDK build

* fix comment

Author: kilograham

src/common/pico_binary_info/CMakeLists.txt

@@ -2,7 +2,11 @@ add_library(pico_binary_info_headers INTERFACE)
 
 target_include_directories(pico_binary_info_headers INTERFACE ${CMAKE_CURRENT_LIST_DIR}/include)
 
-pico_add_impl_library(pico_binary_info)
+if (COMMAND pico_add_platform_library)
+    pico_add_platform_library(pico_binary_info)
+else()
+    add_library(pico_binary_info INTERFACE)
+endif()
 
 target_link_libraries(pico_binary_info INTERFACE pico_binary_info_headers)
 

src/host/pico_platform/CMakeLists.txt

@@ -1,3 +1,5 @@
+# This file may be included directly by a build to get common SDK macros and types
+
 if (NOT TARGET pico_platform_headers)
     add_library(pico_platform_headers INTERFACE)
 
@@ -11,7 +13,11 @@ if (NOT TARGET pico_platform_headers)
 endif()
 
 if (NOT TARGET pico_platform)
-    pico_add_impl_library(pico_platform)
+    if (COMMAND pico_add_platform_library)
+        pico_add_platform_library(pico_platform)
+    else()
+        add_library(pico_platform INTERFACE)
+    endif()
 
     target_sources(pico_platform INTERFACE
         ${CMAKE_CURRENT_LIST_DIR}/platform_base.c
@@ -22,4 +28,4 @@ endif()
 
 function(pico_add_platform_library TARGET)
     target_link_libraries(pico_platform INTERFACE ${TARGET})
-endfunction()
+endfunction()