libmphoenix: separate math.h from libphoenix (draft)

[niewim19]

JIRA: PD-242

Description

• Changes that separate math related functions into libmphoenix.a library (analogy to libm.a library)
• math.h functions are not moved from libphoenix directory

Motivation and Context

• For Micropython compatibility there are plans of expanding math.h header with more functions (gamma, etc.). Separating mathematic functions into libmphoenix.a library is an avoidance of libphoenix size bloating due to mentioned development plans.
• Proposed changes were tested on ia32-generic distribution with additional changes in phoenix-rtos-build/Makefile.ia32 so that PHOENIXLIBM variable was added as presented below:

PHOENIXLIB := $(shell $(CC) $(CFLAGS) -print-file-name=libphoenix.a)
PHOENIXLIBM := $(shell $(CC) $(CFLAGS) -print-file-name=libmphoenix.a)
LDLIBS := $(PHOENIXLIB) $(PHOENIXLIBM) $(GCCLIB) $(CRTBEGIN) $(CRTEND)

All changes now available in:

• libm: add separate variables for math library compilation phoenix-rtos-build#105

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

How Has This Been Tested?

• Already covered by automatic testing.
• New test added: (add PR link here).
• Tested by hand on: (list targets here).
• Tested with use of phoenix-rtos-project draft submodule update:
  • libphoenix: separation of libm from libphoenix test phoenix-rtos-project#345)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing linter checks and tests passed.
• My changes generate no new compilation warnings for any of the targets.

Special treatment

• This PR needs additional PRs to work:
  • libm: add separate variables for math library compilation phoenix-rtos-build#105
• I will merge this PR by myself when appropriate.