In ghci, reload after :e. Patch from Paolo Capriotti. Fixes #5343

MERGED from commit e212079dce3b86df4124d4dd819640f85f479a71
Tweak to flag parsing (#5921)

-o2/Main.exe should be an invalid flag, not a linker input

MERGED from commit 93299cce9a4f7bc65b8164f779a37ef7f9f7c4a0
hp2ps: escape backslashes when generating output file (#5800).

MERGED from commit ee8bf699516dd8e603e26a7c862538e83da2c250
PPC ppr: tabs -> spaces.

MERGED from commit 857cd8edc4ab10286466e6ff6153766ba1e9d905
PPC: Handle right shift of > 31 bits. Fix #5999.

MERGED from commit 42c8e80165bb087493b95a768bbbf276870c7056
Fix closure_type_names, BLACKHOLE and BLOCKING_QUEUE were swapped

MERGED from commit 4bbe9f719f4c26e7f2d8e5a3a8096ac956e1be6c
llvmGen: Use new fence instruction

Signed-off-by: David Terei <davidterei@gmail.com>

MERGED from commit 766da942097613fed56417e3e149997812f83105
Improve support for LLVM >= 3.0 write barrier. (#5814)

MERGED from commit d2d5ee16cf21c5b32333ff57ba0a65f89ff7e988
fix #5534 (ghci -fobject-code strangeness)

MERGED from commit 9fa9dd773fc10a89b05d1456cfe55b79c5bd608c
Update the user guide with details on new flag +RTS -lu

It's for user events emitted from Haskell code, like traceEvent.
Fixes #5790

MERGED from commit 050f714150282695746534174c4550c90c2d9f4e
Add linker support for ELF on ARM

Add support for ELF objects on ARM to the runtime linker. While the list of
relocation types in the "ELF for the ARM Architecture" specification spans four
pages, we thankfully only see a handful of these in the wild. Thus, at the
moment we only support the following .rel relocation types,

 * R_ARM_ABS32
 * R_ARM_TARGET1
 * R_ARM_REL32
 * R_ARM_CALL
 * R_ARM_JUMP24
 * R_ARM_MOVT_ABS
 * R_ARM_MOVW_ABS_NC
 * R_ARM_THM_CALL
 * R_ARM_THM_JUMP24
 * R_ARM_THM_MOVT_ABS
 * R_ARM_THM_MOVW_ABS_NC
 * R_ARM_THM_JUMP8
 * R_ARM_THM_JUMP11

Signed-off-by: Ben Gamari <bgamari.foss@gmail.com>

MERGED from commit b22501b408ddb0503a06a188b06d9cff9be697cd
Update documentation of DatatypeContexts (#5964)

MERGED from commit ac2fbb4f6ce7bf9f0742207e1b974bbd556af85a
Respect package qualifier when validating imports in GHCi (#5979)

MERGED from commit a39a19254003f593e49fa0b29c8a10444cc204c2
Fix a bug in threadStackOverflow() (maybe #5214)

If we overflow the current stack chunk and copy its entire contents
into the next stack chunk, we could end up with two UNDERFLOW_FRAMEs.
We had a special case to catch this in the case when the old stack
chunk was the last one (ending in STOP_FRAME), but it went wrong for
other chunks.

I found this bug while poking around in the core dump attached to
options and running the nofib suite: imaginary/wheel_sieve2 crashed
with +RTS -kc600 -kb300.

I don't know if this is the cause of all the symptoms reported in

MERGED from commit 734f1d484b12b785795b249b4116cfb4817ab55d
Add release notes for 7.4.2.
Revert "Refer to Control.Concurrent instead of GHC.Conc"

This reverts commit 6a217ed6f10d440902eb166d2e0ab4127eb3f699.
Make the LocalRdrEnv keep track of all the Names that are in scope

This allows us to give a sensible error message when a Template Haskell
splice generates an occurrence without a binding site.

Fixes Trac #5959 and #5971

MERGED from commit cb5a3f2d66e4dac2f6f44f56e365d18df884c943
Prevent nested TH exceptions from bubbling up to the top level (#5976)

MERGED from commit e7e5e277eb58a5ef6207200174e7982fdb9780bb
Fix tracking of reason safe inference failed. (#5988)
Update safe haskell error/warn formatting