[build] Silence non-fatal gfortran: command not found errors (#44554)

We build without `gfortran` pretty regularly these days, let's make it
slightly less annoying to build without a `gfortran` available on the
path.

Make.inc

@@ -647,8 +647,8 @@ ifeq ($(OS),FreeBSD)
 ifneq (,$(findstring gfortran,$(FC)))
 
 # First let's figure out what version of GCC we're dealing with
-_GCCMAJOR := $(shell $(FC) -dumpversion | cut -d'.' -f1)
-_GCCMINOR := $(shell $(FC) -dumpversion | cut -d'.' -f2)
+_GCCMAJOR := $(shell $(FC) -dumpversion 2>/dev/null | cut -d'.' -f1)
+_GCCMINOR := $(shell $(FC) -dumpversion 2>/dev/null | cut -d'.' -f2)
 
 # The ports system uses major and minor for GCC < 5 (e.g. gcc49 for GCC 4.9), otherwise major only
 ifeq ($(_GCCMAJOR),4)

deps/csl.mk

@@ -1,6 +1,6 @@
 # Interrogate the fortran compiler (which is always GCC based) on where it is keeping its libraries
-STD_LIB_PATH := $(shell LANG=C $(FC) -print-search-dirs | grep '^programs: =' | sed -e "s/^programs: =//")
-STD_LIB_PATH += :$(shell LANG=C $(FC) -print-search-dirs | grep '^libraries: =' | sed -e "s/^libraries: =//")
+STD_LIB_PATH := $(shell LANG=C $(FC) -print-search-dirs 2>/dev/null | grep '^programs: =' | sed -e "s/^programs: =//")
+STD_LIB_PATH += :$(shell LANG=C $(FC) -print-search-dirs 2>/dev/null | grep '^libraries: =' | sed -e "s/^libraries: =//")
 ifneq (,$(findstring CYGWIN,$(BUILD_OS))) # the cygwin-mingw32 compiler lies about it search directory paths
 STD_LIB_PATH := $(shell echo '$(STD_LIB_PATH)' | sed -e "s!/lib/!/bin/!g")
 endif