Few build changes to support Freebsd (#14121)

* also look for python27

* add more locations to search for lldb.h so it just work on FreeBSD

* add adm64 to ARCH selection. This is mostly cosmetic to avoild warning on FreeBSD

* add support for -osgroup=XXX - this is mostly for conistency. -OSGroup=FreeBSD is similar to freebsdmscorlib in build.cmd

* fix typo adm->amd

* add back fi removed by mistake

* add __HostDistroRid for FreeBSD

* adress fedback from review: make python lookup consistent - starting with most specific version. uddate warning message about lldb.h and remove composite flag

* feedback from review: type and small change on OSGroup syntax

* few more minor fixes

1 files changed, 21 insertions, 1 deletions

diff --git a/build.sh b/build.sh
index ce5e4fbce8..fd21a43ee2 100755
--- a/build.sh
+++ b/build.sh
@@ -2,7 +2,7 @@
 
 # resolve python-version to use
 if [ "$PYTHON" == "" ] ; then
-    if ! PYTHON=$(command -v python || command -v python2 || command -v python 2.7)
+    if ! PYTHON=$(command -v python2.7 || command -v python2 || command -v python)
     then
        echo "Unable to locate build-dependency python2.x!" 1>&2
        exit 1
@@ -74,6 +74,10 @@ initHostDistroRid()
             fi
         fi
     fi
+    if [ "$__HostOS" == "FreeBSD" ]; then
+        __freebsd_version=`sysctl -n kern.osrelease | cut -f1 -d'.'`
+        __HostDistroRid="freebsd.$__freebsd_version-$__HostArch"
+    fi
 
     if [ "$__HostDistroRid" == "" ]; then
         echo "WARNING: Can not determine runtime id for current distro."
@@ -107,6 +111,8 @@ initTargetDistroRid()
             export __DistroRid="linux-$__BuildArch"
         elif [ "$__BuildOS" == "OSX" ]; then
             export __DistroRid="osx-$__BuildArch"
+        elif [ "$__BuildOS" == "FreeBSD" ]; then
+            export __DistroRid="freebsd-$__BuildArch"
         fi
     fi
 }
@@ -553,6 +559,10 @@ case $CPUName in
         __HostArch=arm64
         ;;
 
+    amd64)
+        __BuildArch=x64
+        __HostArch=x64
+        ;;
     *)
         echo "Unknown CPU $CPUName detected, configuring as if for x64"
         __BuildArch=x64
@@ -860,6 +870,16 @@ while :; do
               exit 1
             fi
             ;;
+        osgroup|-osgroup)
+            if [ -n "$2" ]; then
+              __BuildOS="$2"
+              shift
+            else
+              echo "ERROR: 'osgroup' requires a non-empty option argument"
+              exit 1
+            fi
+            ;;
+
         *)
             __UnprocessedBuildArgs="$__UnprocessedBuildArgs $1"
             ;;