libjulia_jll: turn LibOSXUnwind_jll into a build dep for Julia 1.6

L/libjulia/build_tarballs.jl

@@ -1,5 +1,5 @@
 include("common.jl")
-jllversion=v"1.7.0"
+jllversion=v"1.7.1"
 build_julia(ARGS, v"1.6.3"; jllversion)
 build_julia(ARGS, v"1.7.0"; jllversion)
 build_julia(ARGS, v"1.8.0-DEV"; jllversion)

L/libjulia/bundled/julia-1.6-libunwind.patch

@@ -0,0 +1,65 @@
+diff --git a/src/julia_internal.h b/src/julia_internal.h
+index 0b76696791..f6bd2f1f3f 100644
+--- a/src/julia_internal.h
++++ b/src/julia_internal.h
+@@ -893,48 +893,7 @@ typedef struct {
+
+ // Might be called from unmanaged thread
+ uint64_t jl_getUnwindInfo(uint64_t dwBase);
+-#ifdef _OS_WINDOWS_
+-#include <dbghelp.h>
+-JL_DLLEXPORT EXCEPTION_DISPOSITION __julia_personality(
+-        PEXCEPTION_RECORD ExceptionRecord, void *EstablisherFrame, PCONTEXT ContextRecord, void *DispatcherContext);
+-extern HANDLE hMainThread;
+-typedef CONTEXT bt_context_t;
+-#if defined(_CPU_X86_64_)
+-typedef CONTEXT bt_cursor_t;
+-#else
+-typedef struct {
+-    STACKFRAME64 stackframe;
+-    CONTEXT context;
+-} bt_cursor_t;
+-#endif
+-extern jl_mutex_t jl_in_stackwalk;
+-#elif !defined(JL_DISABLE_LIBUNWIND)
+-// This gives unwind only local unwinding options ==> faster code
+-#  define UNW_LOCAL_ONLY
+-#  include <libunwind.h>
+-typedef unw_context_t bt_context_t;
+-typedef unw_cursor_t bt_cursor_t;
+-#  if (!defined(SYSTEM_LIBUNWIND) || UNW_VERSION_MAJOR > 1 ||   \
+-       (UNW_VERSION_MAJOR == 1 && UNW_VERSION_MINOR != 0 && UNW_VERSION_MINOR != 1))
+-// Enable our memory manager only for libunwind with our patch or
+-// on a newer release
+-#    define JL_UNW_HAS_FORMAT_IP 1
+-#  endif
+-#else
+-// Unwinding is disabled
+-typedef int bt_context_t;
+-typedef int bt_cursor_t;
+-#endif
+-size_t rec_backtrace(jl_bt_element_t *bt_data, size_t maxsize, int skip) JL_NOTSAFEPOINT;
+-// Record backtrace from a signal handler. `ctx` is the context of the code
+-// which was asynchronously interrupted.
+-size_t rec_backtrace_ctx(jl_bt_element_t *bt_data, size_t maxsize, bt_context_t *ctx,
+-                         jl_gcframe_t *pgcstack) JL_NOTSAFEPOINT;
+-#ifdef LIBOSXUNWIND
+-size_t rec_backtrace_ctx_dwarf(jl_bt_element_t *bt_data, size_t maxsize, bt_context_t *ctx, jl_gcframe_t *pgcstack) JL_NOTSAFEPOINT;
+-#endif
+ JL_DLLEXPORT jl_value_t *jl_get_backtrace(void);
+-void jl_critical_error(int sig, bt_context_t *context);
+ JL_DLLEXPORT void jl_raise_debugger(void);
+ int jl_getFunctionInfo(jl_frame_t **frames, uintptr_t pointer, int skipC, int noInline) JL_NOTSAFEPOINT;
+ JL_DLLEXPORT void jl_gdblookup(void* ip) JL_NOTSAFEPOINT;
+diff --git a/src/julia_threads.h b/src/julia_threads.h
+index f42984130f..8a8411f822 100644
+--- a/src/julia_threads.h
++++ b/src/julia_threads.h
+@@ -67,7 +67,6 @@ typedef struct {
+ #endif
+ #if defined(JL_HAVE_UCONTEXT) || defined(JL_HAVE_UNW_CONTEXT)
+ #define UNW_LOCAL_ONLY
+-#include <libunwind.h>
+ typedef struct {
+     ucontext_t ctx;
+ #if defined(JL_TSAN_ENABLED)

L/libjulia/common.jl

@@ -268,6 +268,14 @@ function build_julia(ARGS, version::VersionNumber; jllversion=version)
     # environment results in a segfault.
     make USE_CROSS_FLISP=1 NO_GIT=1 LDFLAGS="${LDFLAGS}" CFLAGS="${CFLAGS}" CXXFLAGS="${CXXFLAGS}" -j${nproc} VERBOSE=1 ${MAKE_TARGET} DSYMUTIL=true
 
+    # HACK to avoid runtime dependency on LibOSXUnwind_jll with Julia 1.6: it
+    # disables the `#include <libunwind.h>` statements in two header files,
+    # and all code directly depending on them; luckily all of that is internal
+    # and should not affect external code using the Julia kernel "API"
+    if [[ "${version}" == 1.6.* ]]; then
+        atomic_patch -p1 $WORKSPACE/srcdir/julia-1.6-libunwind.patch
+    fi
+
     # 'manually' install libraries and headers
     mkdir -p ${libdir}
     mkdir -p ${includedir}/julia
@@ -314,7 +322,7 @@ function build_julia(ARGS, version::VersionNumber; jllversion=version)
     if version < v"1.5.1"
         push!(dependencies, Dependency("LibOSXUnwind_jll", compat="0.0.5"))
     elseif version < v"1.7"
-        push!(dependencies, Dependency("LibOSXUnwind_jll", compat="0.0.6"))
+        push!(dependencies, BuildDependency("LibOSXUnwind_jll", compat="0.0.6"))
     end
 
     if version < v"1.6"