use_mxmat = .false. causes min_gddmaturity warnings

### Brief summary of bug

Setting `use_mxmat = .false.` in an otherwise normal run unexpectedly causes lots of warnings like this:
```
dec2331.hsn.de.hpc.ucar.edu 1813: Some patch with ivt 68 has rx gddmaturity 1.240569649612944E-023
dec2331.hsn.de.hpc.ucar.edu 1813: ; using min_gddmaturity instead ( 1.00000000000000 )
dec2331.hsn.de.hpc.ucar.edu 1821: Some patch with ivt 67 has rx gddmaturity 1.118450637000431E-023
dec2331.hsn.de.hpc.ucar.edu 1821: ; using min_gddmaturity instead ( 1.00000000000000 )
```

### General bug information

**CTSM version you are using:** `alpha-ctsm5.4.CMIP7.09.ctsm5.3.068-12-gc5d0b3089` (need to test with a real tag)

**Does this bug cause significantly incorrect results in the model's science?** Unknown

**Configurations affected:** Crop runs where a user changes this setting.

### Details of bug

[Fill in details here.]

### Important details of your setup / configuration so we can reproduce the bug

Compset longname is `HIST_DATM%CRUJRA2024_CLM60%BGC-CROP_SICE_SOCN_MOSART_SGLC_SWAV_SESP`. f09 resolution.

`user_nl_clm`:
```
hist_empty_htapes = .true.

! Set up h0 file
hist_nhtfrq(1) = 17520 ! annual saves
hist_mfilt(1) = 1 ! new file every save (so annual files)
hist_type1d_pertape(1) = 'PFTS'
hist_dov2xy(1) = .false.

! Instantaneous annual crop variables
hist_fincl1 = 'GRAINC_TO_FOOD_PERHARV', 'GRAINC_TO_FOOD_ANN', 'SDATES', 'SDATES_PERHARV', 'SYEARS_PERHARV', 'HDATES', 'GDDHARV_PERHARV', 'GDDACCUM_PERHARV', 'HUI_PERHARV', 'SOWING_REASON_PERHARV', 'HARVEST_REASON_PERHARV'

! Non-instantaneous (e.g. average or max) crop variables
! Keep at least one of these on h0 to avoid this issue: https://github.com/ESCOMP/CTSM/issues/3451
hist_fincl1 += 'GDD0', 'GDD8', 'GDD10', 'GDD0X', 'GDD8X', 'GDD10X', 'GDD020', 'GDD820', 'GDD1020'

hist_fincl1 += 'MAXLAIGRAINFILL', 'MAXLAIGRAINFILL_PERHARV', 'CROPPHASE_TIME_PRE_PERHARV', 'CROPPHASE_TIME_VEG_PERHARV', 'CROPPHASE_TIME_REP_PERHARV'

stream_fldFileName_gdd20_baseline = '/glade/work/samrabin/gdd20_baselines/20251010_cropcals_1deg.actually2deg.1980-2009.from_GDDB20.clm6_crop_032.interp_halfdeg_tweaked.nc'

use_mxmat = .false.
```
### Important output or errors that show the problem

This run also ended with `SIGTERM`; not sure if it's related:
```
dec1514.hsn.de.hpc.ucar.edu 1: Abort with message NetCDF: HDF error in file /glade/derecho/scratch/csgteam
/temp/spack/derecho/24.12/builds/spack-stage-parallelio-2.6.6-5oefk2r5g2vtjc6igyiallo5pe5q6zep/spack-src/s
rc/clib/pio_darray_int.c at line 1678
...
dec1068.hsn.de.hpc.ucar.edu 768: forrtl: error (78): process killed (SIGTERM)
dec1068.hsn.de.hpc.ucar.edu 768: Image PC Routine Line Sourc
e
dec1068.hsn.de.hpc.ucar.edu 768: libpthread-2.31.s 00001456804898C0 Unknown Unknown Unkno
wn
dec1068.hsn.de.hpc.ucar.edu 768: cesm.exe 0000000000CE42F8 soilbiogeochemnit 1059 SoilB
iogeochemNitrogenFluxType.F90
dec1068.hsn.de.hpc.ucar.edu 768: cesm.exe 0000000000FB376E cndrivermod_mp_cn 288 CNDri
verMod.F90
dec1068.hsn.de.hpc.ucar.edu 768: cesm.exe 000000000094052B cnvegetationfacad 1030 CNVeg
etationFacade.F90
dec1068.hsn.de.hpc.ucar.edu 768: cesm.exe 00000000005FB7BF clm_driver_mp_clm 1058 clm_d
river.F90
dec1068.hsn.de.hpc.ucar.edu 768: cesm.exe 000000000059FF61 lnd_comp_nuopc_mp 904 lnd_c
omp_nuopc.F90
```