Makefile: allow to build debug version nydusd

[bergwolf]

Relevant Issue (if applicable)

none.

Details

We still build the release version by default, but make sure that make build only generates a debug version nydusd.

Types of changes

What types of changes does your PullRequest introduce? Put an x in all the boxes that apply:

• 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)
• Documentation Update (if none of the other choices apply)

Checklist

• I have updated the documentation accordingly.
• I have added tests to cover my changes.

[anolis-bot]

@bergwolf , a new test job has been submitted. Please wait in patience. The test job url: https://tone.openanolis.cn/ws/nrh4nnio/test_result/84209

[codecov]

Codecov Report

Merging #1369 (ae58c3b) into master (c8a39c8) will decrease coverage by 0.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1369      +/-   ##
==========================================
- Coverage   46.01%   45.94%   -0.07%     
==========================================
  Files         122      122              
  Lines       37807    37807              
  Branches    37807    37807              
==========================================
- Hits        17396    17372      -24     
- Misses      19502    19525      +23     
- Partials      909      910       +1     

see 6 files with indirect coverage changes

[anolis-bot]

@bergwolf , The CI test is completed, please check result:

Test Case		Test Result
build rust golang image		✅ SUCCESS
compile nydusd		✅ SUCCESS
compile ctr remote		✅ SUCCESS
compile nydus snapshotter		✅ SUCCESS
run container with rafs		✅ SUCCESS
run container with zran		✅ SUCCESS
run container with rafs and compile linux		✅ SUCCESS

Congratulations, your test job passed!