package/libeastl: needs threads

libeastl needs threads since its addition in commit
ed9ddaafb2c4d3ac44e46390248f5c9af08076b1 and
https://github.com/electronicarts/EASTL/commit/800bc26659f834354e38ee3de4c7300e739ed255:

In file included from /home/autobuild/autobuild/instance-7/output-1/build/libeastl-45469730d641868ce05433fff2e199510c7d45c3/source/thread_support.cpp:7:
/home/autobuild/autobuild/instance-7/output-1/build/libeastl-45469730d641868ce05433fff2e199510c7d45c3/include/EASTL/internal/thread_support.h:37:18: fatal error: pthread.h: No such file or directory
   37 |         #include <pthread.h>
      |                  ^~~~~~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/54ff018467d157530bde4d35602fd1820d9eb348

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 4c478bb0554e8cd8faf62fe2d3a6dc2e68fa7c7b)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libeastl/Config.in

@@ -11,6 +11,7 @@ config BR2_PACKAGE_LIBEASTL
 	depends on BR2_PACKAGE_LIBEASTL_ARCH_SUPPORTS
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 # C++14
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	help
 	  EASTL stands for Electronic Arts Standard Template
 	  Library. It is a C++ template library of containers,
@@ -21,6 +22,7 @@ config BR2_PACKAGE_LIBEASTL
 
 	  https://github.com/electronicarts/EASTL
 
-comment "libeastl needs a toolchain w/ C++, gcc >= 4.9"
+comment "libeastl needs a toolchain w/ C++, threads, gcc >= 4.9"
 	depends on BR2_PACKAGE_LIBEASTL_ARCH_SUPPORTS
-	depends on !BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 || !BR2_INSTALL_LIBSTDCPP
+	depends on !BR2_TOOLCHAIN_GCC_AT_LEAST_4_9 || \
+		!BR2_TOOLCHAIN_HAS_THREADS || !BR2_INSTALL_LIBSTDCPP