WIP: py 3.6 enable bitcode, bump numpy to 1.16.3

[dalcacer]

This pull request enables bitcode for all Python 3.6 builds and supporting libs. It further focuses on enabling numpy 1.16.3 on iOS and was tested on actual devices and the simulator.

Trivia

• enabling bitcode for iOS projects is default, but not mandatory.
• when the according XCode setting is enabled, the given python + numpy builds will not run on actual devices (simulator works, though)
• when the fembed-bitcode flag is set, the given build process breaks
• linker flags such as dyanmic_lookup and bundle won't work anymore
• numpy 1.16.3 contains @freakboy3742 's upstream patch for cross compilation

Approach

• -fembed-bitcode was enabled for all iOS builds
• environment variable LDSHARED used to further control cython numpy-build and linking
• linker flag -undefined dyanmic_lookup disabled: environment variable LDLIB was introduced to further control cython numpy-build and linking. Numpy was patched to recognize this non-std. variable. Std. variables (LD_LIBRARY_PATH and others) were not recognized by build script.
• linker flag -undefined dyanmic_lookup disabled: numpy was patched to name necessary libs.
• numpy random module was patched to circumvent runtime error that tries an local include of mtrand
• linker flag - bundle substituted with bitcode compatible flag -r.
• numpy startup/inclusion method was altered, due to merge of multiarray and umath (see README.rst)
• build target dist/{iOS/tvOS/watchOS}/app_packages/numpy introduced

Todo

• [ ] check, review, discuss, enhance presented approach
• [ ] check warnings and error that are thrown when building numpy-iOS (skim for major flaws/problems)
• [ ] remove -Wall compile flag here
• [ ] undo bzip-url commit
• [ ] re-enable and test macOS/tvOS/watchOS build

For our build the following platforms were selected (makefile)

# Supported OS
# OS=macOS iOS tvOS watchOS
# limit build to macOS iOS
OS=macOS iOS

[dalcacer]

The PR (in general) also works for 3.7. The only difference is the patched list of libraries (python3.7m instead of python3.6m).

[dalcacer]

Closing merge request, because of deprecation.