Use capi instead of ccall for stat/lstat on macOS

On macOS, stat is remapped via macros in sys/stat.h to a 64-bit
variant. Using ccall bypassed this remapping causing st_mode to be
read at the wrong offset, misidentifying symlinks as regular files
and breaking followSymlinks.

Author: harendra-kumar

core/docs/Changelog.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+# Bug fix: Fixed `followSymlinks` option not working correctly on macOS.
+
 ## 0.3.0
 
 See [0.2.2-0.3.0 API Changelog](/core/docs/ApiChangelogs/0.2.2-0.3.0.txt) for a

core/src/Streamly/Internal/FileSystem/Posix/ReadDir.hsc

@@ -144,10 +144,10 @@ foreign import capi unsafe "dirent.h readdir"
 -- Stat
 --------------------------------------------------------------------------------
 
-foreign import ccall unsafe "stat.h lstat"
+foreign import capi unsafe "sys/stat.h lstat"
     c_lstat :: CString -> Ptr CStat -> IO CInt
 
-foreign import ccall unsafe "stat.h stat"
+foreign import capi unsafe "sys/stat.h stat"
     c_stat :: CString -> Ptr CStat -> IO CInt
 
 s_IFMT :: CMode