increase char len for cpp path

[annlew]

Summary: Increase the char length for path to compiler in chem_pp code

Contributors: @annlew, @sarambl

Reviewers: @gold2718

Purpose of changes: Avoid chemistry preprocessor failure at compilation when path to compiler exceeds 64 characters

Github PR URL: #161

Changes made to build system: Only chemistry preprocessor when usr_mech_infile is specified in env_build.xml

Changes made to the namelist: None

Changes to the defaults for the boundary datasets: None

Substantial timing or memory changes: None

Change the char length for cpp path from 64 to 256 in chem_pp code.

Test: SMS allactive test with grid = f19_tn14 and compset=NF2000climo with a testmod to run the chemistry preprocessor. Fails with current HEAD of noresm2_1_develop, passes with this PR branch.

Issues addressed by this PR:
cam_chempp issue with usr_mech_infile when path to compiler is too long (#160)

addresses #160

[gold2718]

Looks good, thanks!

[gold2718]

Please let me know when you have successfully run a test which previously failed.

[annlew]

Tests:

SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem

mychem/shell_commands

cp  /proj/bolinc/users/x_alewi/NorESM2/noresm_el9/cases/cpp_chem_test2/my_chem_mech.in .
./xmlchange --append CAM_CONFIG_OPTS="--usr_mech_infile `pwd`/my_chem_mech.in"

Branch noresm2_1_develop with cam branch NorESMhub:noresm2_1_develop

PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem CREATE_NEWCASE
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem XML
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem SETUP
FAIL SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem SHAREDLIB_BUILD time=1

REMOVE <noresm-base>/components/cam/chem_proc/campp

Branch noresm2_1_develop with cam branch annlew:noresm2_1_dev_chempp_bug

PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem CREATE_NEWCASE
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem XML
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem SETUP
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem SHAREDLIB_BUILD time=340
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem MODEL_BUILD time=235
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem SUBMIT
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem RUN time=845
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem MEMLEAK insuffiencient data for memleak test
PASS SMS.f19_tn14.NF2000climo.tetralith_intel.allactive-mychem SHORT_TERM_ARCHIVER

[gold2718]

This test looks great but also potentially useful.
It will not affect this PR but I suggest we add the new* testmods_dirs/allactive directory to NorESM. Thoughts?

*I do not see it in noresm2_1_develop