build: Set shared linker flags in toolchain file

These are required when cross-compiling shared libraries such as the
kernel library.

Author: TheCharlatan

depends/toolchain.cmake.in

@@ -55,12 +55,21 @@ set(DEPENDS_COMPILE_DEFINITIONS_DEBUG @CPPFLAGS_DEBUG@)
 if(NOT DEFINED CMAKE_EXE_LINKER_FLAGS_INIT)
   set(CMAKE_EXE_LINKER_FLAGS_INIT "@LDFLAGS@")
 endif()
+if(NOT DEFINED CMAKE_SHARED_LINKER_FLAGS_INIT)
+  set(CMAKE_SHARED_LINKER_FLAGS_INIT "@LDFLAGS@")
+endif()
 if(NOT DEFINED CMAKE_EXE_LINKER_FLAGS_RELWITHDEBINFO_INIT)
   set(CMAKE_EXE_LINKER_FLAGS_RELWITHDEBINFO_INIT "@LDFLAGS_RELEASE@")
 endif()
+if(NOT DEFINED CMAKE_SHARED_LINKER_FLAGS_RELWITHDEBINFO_INIT)
+  set(CMAKE_SHARED_LINKER_FLAGS_RELWITHDEBINFO_INIT "@LDFLAGS_RELEASE@")
+endif()
 if(NOT DEFINED CMAKE_EXE_LINKER_FLAGS_DEBUG_INIT)
   set(CMAKE_EXE_LINKER_FLAGS_DEBUG_INIT "@LDFLAGS_DEBUG@")
 endif()
+if(NOT DEFINED CMAKE_SHARED_LINKER_FLAGS_DEBUG_INIT)
+  set(CMAKE_SHARED_LINKER_FLAGS_DEBUG_INIT "@LDFLAGS_DEBUG@")
+endif()
 
 set(CMAKE_AR "@AR@")
 set(CMAKE_RANLIB "@RANLIB@")