The idea is to move all pieces related to the actual libc sources to the
"src" directory. This allows downstream users to ship and build just the
"src" directory.

Reviewed By: michaelrj

Differential Revision: https://reviews.llvm.org/D112653

Also, this adds unit tests to check that limits.h complies with the C
standard.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D110643

Some ctype functions are called from other libc functions (e.g. isspace
is used in atoi). By moving ctype_utils.h to __support it becomes easier
to include just the implementations of these functions. For these
reasons the implementation for isspace was moved into
ctype_utils as well.

FPUtils was moved to simplify the build order, and to clarify which
files are a part of the actual libc.

Many files were modified to accomodate these changes, mostly changing
the #include paths.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D107600

This addition reads command line input to run specific single tests
within a larger call to run all the tests for a particular function.
When the user adds a second argument to the command line, the code skips
all the tests that don't match the user's specified binary. If the user
doesn't specify a test correctly and/or no tests are run, a failure
message prints.

Reviewed By: sivachandra, aeubanks

Differential Revision: https://reviews.llvm.org/D105843

Different platforms treat size_t differently so we should compare sizes
of ArrayRef objects with size_t values (instead of the current unsigned
long values.)

Current implementation defines LIBC_TARGET_MACHINE with the use of CMAKE_SYSTEM_PROCESSOR.
Unfortunately CMAKE_SYSTEM_PROCESSOR is OS dependent and can produce different results.
An evidence of this is the various matchers used to detect whether the architecture is x86.

This patch normalizes LIBC_TARGET_MACHINE and renames it LIBC_TARGET_ARCHITECTURE.
I've added many architectures but we may want to limit ourselves to x86 and ARM.

Differential Revision: https://reviews.llvm.org/D101524

This patch mostly adds unittests for `ArrayRef` and `MutableArrayRef`, additionnaly:
 - We mimic the behavior of `std::vector` and disallow CV qualified type (`ArrayRef<const X>` is not allowed).
   This is to make sure that the type traits are always valid (e.g. `value_type`, `pointer`, ...).
 - In the previous implementation `ArrayRef` would define `value_type` as `const T` but this is not correct, it should be `T` for both `MutableArrayRef` and `ArrayRef`.
 - We add the `equals` method to ease testing,
 - We define the constructor taking an `Array` outside of the base implementation to ensure we match `const Array<T>&` and not `Array<const T>&` in the case of `ArrayRef`.

Differential Revision: https://reviews.llvm.org/D100732

This option will build LLVM libc as a full libc by itself. In this mode,
it is not expected that it will be mixed with other libcs. The
non-full-build mode will be the default LLVM libc build mode. In a future
where LLVM libc is complete enough, the full libc build will be made the
default mode.

This class is to serve as a replacement for llvm::StringRef as part of
the plans to limit dependency on other parts of LLVM. One use of
llvm::StringRef in MPFRWrapper has been replaced with the new class.

Reviewed By: lntue

Differential Revision: https://reviews.llvm.org/D97330

Summary:
Having a consistent prefix makes selecting all of the llvm libc tests
easier on any platform that is also using the gtest framework.
This also modifies the TEST and TEST_F macros to enforce this change
moving forward.

Reviewers: sivachandra

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