strip --keep-section=.llvmbc is not supported on macOS

* $ graalvm/languages/llvm/native/bin/strip --keep-section=.llvmbc stripped.bundle
  graalvm/lib/llvm/bin/llvm-strip: error: option not supported by llvm-objcopy for MachO
* Fixes #2697

Author: eregon

CHANGELOG.md

@@ -10,6 +10,7 @@ Bug fixes:
 * Fix `StringIO` to set position correctly after reading multi-byte characters (#2207, @aardvark179).
 * Update `Process` methods to use `module_function` (@bjfish).
 * Fix `File::Stat`'s `#executable?` and `#executable_real?` predicates that unconditionally returned `true` for a superuser (#2690, @andrykonchin).
+* The `strip` option `--keep-section=.llvmbc` is not supported on macOS (#2697, @eregon).
 
 Compatibility:
 

lib/cext/ABI_version.txt

@@ -1 +1 @@
-7
+8

lib/truffle/rbconfig.rb

@@ -68,6 +68,8 @@ module RbConfig
   ranlib = Truffle::Boot.toolchain_executable(:RANLIB)
   strip = Truffle::Boot.toolchain_executable(:STRIP)
 
+  strip = "#{strip} --keep-section=.llvmbc" unless Truffle::Platform.darwin?
+
   # Determine the various flags for native compilation
   optflags = ''
   debugflags = ''
@@ -188,7 +190,7 @@ module RbConfig
     'rubyarchhdrdir'    => rubyhdrdir.dup,
     'rubyhdrdir'        => rubyhdrdir,
     'SOEXT'             => Truffle::Platform::SOEXT.dup,
-    'STRIP'             => "#{strip} --keep-section=.llvmbc",
+    'STRIP'             => strip,
     'sysconfdir'        => "#{prefix}/etc", # doesn't exist, as in MRI
     'target_cpu'        => host_cpu,
     'target_os'         => host_os,