cmake: make libcap REQUIRED

this header is required when building the extended block device plugins
on linux, without it the build fails like:

```
/home/kefu/dev/ceph/src/extblkdev/ExtBlkDevInterface.h:38:10: fatal error: 'sys/capability.h' file not found
   38 | #include <sys/capability.h>
      |          ^~~~~~~~~~~~~~~~~~
```

so, let's mark this package REQUIRED, so that we can fail early
when generating the building system.

Signed-off-by: Kefu Chai <tchaikov@gmail.com>

diff --git a/src/extblkdev/CMakeLists.txt b/src/extblkdev/CMakeLists.txt
index 27e7c23e4942ff29135e95e5f75e79869c7b02b1..648e5de9e43c72fffbcce297da50886e1f0b7658 100644 (file)
--- a/src/extblkdev/CMakeLists.txt
+++ b/src/extblkdev/CMakeLists.txt
@@ -6,9 +6,9 @@ add_subdirectory(vdo)
 
 add_library(extblkdev STATIC ExtBlkDevPlugin.cc)
 
-if(NOT WIN32)
-find_package(cap)
-target_link_libraries(extblkdev cap)
+if(LINUX)
+  find_package(cap REQUIRED)
+  target_link_libraries(extblkdev cap)
 endif()
 
 add_custom_target(extblkdev_plugins DEPENDS