build: support build with libunwind on osx (#162)

macOS provides a libunwind in SDK, so we can skip the library search
process.

---------

Co-authored-by: Jeremy Rifkin <[email protected]>

Author: Ghost-LZW

CMakeLists.txt

@@ -523,26 +523,28 @@ if(CPPTRACE_UNWIND_WITH_LIBUNWIND)
     endif()
   endif()
   if(NOT libunwind_FOUND)
-    # set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB64_PATHS ON)
-    # set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB32_PATHS ON)
-    find_path(LIBUNWIND_INCLUDE_DIRS NAMES "libunwind.h")
-    find_library(LIBUNWIND NAMES unwind libunwind libunwind8 libunwind.so.8 REQUIRED PATHS "/usr/lib/x86_64-linux-gnu/")
-    if(LIBUNWIND)
-      set(libunwind_FOUND TRUE)
-    endif()
-    if(NOT libunwind_FOUND)
-      # message(FATAL_ERROR "Unable to locate libunwind")
-      # Try to link with it if it's where it should be
-      # This path can be entered if libunwind was installed via the system package manager, sometimes. I probably messed
-      # up the find_library above.
-      set(LIBUNWIND_LDFLAGS "-lunwind")
-    endif()
-    if(NOT LIBUNWIND_LDFLAGS)
-      set(LIBUNWIND_LDFLAGS "${LIBUNWIND}")
+    if (NOT APPLE)
+      # set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB64_PATHS ON)
+      # set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB32_PATHS ON)
+      find_path(LIBUNWIND_INCLUDE_DIRS NAMES "libunwind.h")
+      find_library(LIBUNWIND NAMES unwind libunwind libunwind8 libunwind.so.8 REQUIRED PATHS "/usr/lib/x86_64-linux-gnu/")
+      if(LIBUNWIND)
+        set(libunwind_FOUND TRUE)
+      endif()
+      if(NOT libunwind_FOUND)
+        # message(FATAL_ERROR "Unable to locate libunwind")
+        # Try to link with it if it's where it should be
+        # This path can be entered if libunwind was installed via the system package manager, sometimes. I probably messed
+        # up the find_library above.
+        set(LIBUNWIND_LDFLAGS "-lunwind")
+      endif()
+      if(NOT LIBUNWIND_LDFLAGS)
+        set(LIBUNWIND_LDFLAGS "${LIBUNWIND}")
+      endif()
+      target_compile_options(${target_name} PRIVATE ${LIBUNWIND_CFLAGS_OTHER})
+      target_include_directories(${target_name} PRIVATE ${LIBUNWIND_INCLUDE_DIRS})
+      target_link_libraries(${target_name} PRIVATE ${LIBUNWIND_LDFLAGS})
     endif()
-    target_compile_options(${target_name} PRIVATE ${LIBUNWIND_CFLAGS_OTHER})
-    target_include_directories(${target_name} PRIVATE ${LIBUNWIND_INCLUDE_DIRS})
-    target_link_libraries(${target_name} PRIVATE ${LIBUNWIND_LDFLAGS})
     target_compile_definitions(${target_name} PUBLIC CPPTRACE_UNWIND_WITH_LIBUNWIND UNW_LOCAL_ONLY)
   endif()
 endif()