CMake: Add ucontext

CMakeLists.txt

@@ -61,6 +61,7 @@ if (UNIX)
     find_package(Sigaction)
     find_package(Sigaltstack)
     find_package(SelfDbg)
+    find_package(Ucontext)
 endif (UNIX)
 
 find_package(SSE)

cmake/FindUcontext.cmake

@@ -0,0 +1,23 @@
+include(CheckCXXSourceCompiles)
+
+check_cxx_source_compiles("
+#include <ucontext.h>
+int main() {
+    ucontext_t context;
+#if defined(__x86_64__)
+    void *ptr = (void *) context.uc_mcontext.gregs[REG_RIP];
+#elif defined(__i386)
+    void *ptr = (void *) context.uc_mcontext.gregs[REG_EIP];
+#else
+#error Unknown arch
+#endif
+    return 0;
+}"
+    UCONTEXT_FOUND
+)
+
+if (UCONTEXT_FOUND)
+    add_compile_options(
+        -DWITH_UCONTEXT
+    )
+endif (UCONTEXT_FOUND)