Add RISCV32 support

Upstream-Status: Pending
Signed-off-by: Khem Raj <raj.khem@gmail.com>

--- a/build/moz.configure/init.configure
+++ b/build/moz.configure/init.configure
@@ -765,6 +765,9 @@ def split_triplet(triplet, allow_msvc=Fa
     elif cpu.startswith("aarch64"):
         canonical_cpu = "aarch64"
         endianness = "little"
+    elif cpu in ("riscv32", "riscv32gc"):
+        canonical_cpu = "riscv32"
+        endianness = "little"
     elif cpu in ("riscv64", "riscv64gc"):
         canonical_cpu = "riscv64"
         endianness = "little"
--- a/python/mozbuild/mozbuild/configure/constants.py
+++ b/python/mozbuild/mozbuild/configure/constants.py
@@ -52,6 +52,7 @@ CPU_bitness = {
     "mips64": 64,
     "ppc": 32,
     "ppc64": 64,
+    'riscv32': 32,
     "riscv64": 64,
     "s390": 32,
     "s390x": 64,
@@ -94,6 +95,7 @@ CPU_preprocessor_checks = OrderedDict(
         ("m68k", "__m68k__"),
         ("mips64", "__mips64"),
         ("mips32", "__mips__"),
+        ("riscv32", "__riscv && __riscv_xlen == 32"),
         ("riscv64", "__riscv && __riscv_xlen == 64"),
         ("sh4", "__sh__"),
         ("wasm32", "__wasm32__"),
--- a/python/mozbuild/mozbuild/test/configure/test_toolchain_configure.py
+++ b/python/mozbuild/mozbuild/test/configure/test_toolchain_configure.py
@@ -1186,6 +1186,7 @@ class LinuxCrossCompileToolchainTest(Bas
         "m68k-unknown-linux-gnu": big_endian + {"__m68k__": 1},
         "mips64-unknown-linux-gnuabi64": big_endian + {"__mips64": 1, "__mips__": 1},
         "mips-unknown-linux-gnu": big_endian + {"__mips__": 1},
+        "riscv32-unknown-linux-gnu": little_endian + {"__riscv": 1, "__riscv_xlen": 32},
         "riscv64-unknown-linux-gnu": little_endian + {"__riscv": 1, "__riscv_xlen": 64},
         "sh4-unknown-linux-gnu": little_endian + {"__sh__": 1},
     }