Low: gcc security, bug fix, and enhancement update (Oracle Linux 7)

[4.8.5-28.0.1]
- [Orabug: 27557686] (Egeyar Bagcioglu)
- Introduce 'oracle_release' into .spec file. Echo it to gcc/DEV-PHASE.

[4.8.5-28]
- Minor testsuite fixes to clean up test results (#1469697)
- retpoline support for spectre mitigation (#1535655)

[4.8.5-27]
- bump for rebuild with RELRO enabled even for ppc64/ppc64le

[4.8.5-26]
- Avoid red zone probing for zero residual dynamic allocation (#1469697)
- Avoid bogus CFIs for probes in noreturn fucntions on x86/x86_64 (#1469697)

[4.8.5-25]
- Avoid red zone probe on aarch64 (#1469697)

[4.8.5-24]
- Sync gcc48-rh1469697-13 patch to upstream (#1469697)
- Avoid probing in the red zone for noreturn functions (#1507980, #1469697)
- Avoid infinite loop if probing interval is less than guard size (#1469697)
- Fix debug information for large probing interval on aarch64 (#1469697)
- Fix ICE on ppc port with large probing interval (#1469697)

- rebuild to remove static relocations not known to older linkers (#1508968)

[4.8.5-23]
- rebuild to remove static relocations not known to older linkers (#1508968)

[4.8.5-22]
- fix gcc.c-torture/execute/pr80692.x
- fix divmod expansion (PR middle-end/78416)

[4.8.5-21]
- fix 27_io/basic_fstream/53984.cc
- fix for classes with bases with mutable members (PR c++/77375)
- fix handling side-effects of parameters (PR c/77767)
- fix combine's make_extraction (PR rtl-optimization/78378)
- fix gimplification of const var initialization from COND_EXPR (PR c++/80129)
- fix -A / -B to A / B folding (PR middle-end/80362)
- fix comparison of decimal float zeroes (PR middle-end/80692)
- fix __mulv[dt]i3 and expand_mul_overflow (PR target/82274)

[4.8.5-20]
- handle exceptions in basic_istream::sentry (#1469384)
- don't run pr63354.c on ppc (#1468546)
- ensure proxy privatization safety (#1491395)
- fix incorrect codegen from rdseed intrinsic use (#1482762, CVE-2017-11671)
- on aarch64, remove libatomic.so (#1465510)

[4.8.5-19]
- Backport stack clash protection from upstream (#1469697)

[4.8.5-18]
- backport several -mprofile-kernel fixes (#1468546)

[4.8.5-17]
- fix -mcpu=power8 atomic expansion (#1437220, PR target/69644)
- fix .toc alignment (#1487434)