Linux build, on all my systems, Slackware, Fedora,,,,,

Building C object base/shell/progman/progman_pch.h.gch
FAILED: /usr/local/RosBE/i386/bin/i686-w64-mingw32-gcc  -DDBG=1 -DKDBG=1 -DUNICODE -DUSE_COMPILER_EXCEPTIONS -DWINVER=0x502 -D_DLL -D_M_IX86 -D_SEH_ENABLE_TRACE -D_SETUPAPI_VER=0x502 -D_UNICODE -D_USE_32BIT_TIME_T -D_USE_PSEH3=1 -D_WIN32_IE=0x600 -D_WIN32_WINDOWS=0x502 -D_WIN32_WINNT=0x502 -D_X86_ -D__REACTOS__ -D__USE_CRTIMP -D__i386__ -D_inline=__inline -Di386 -Wa,--compress-debug-sections -pipe -fms-extensions -fno-strict-aliasing -nostdinc -mstackrealign -Wold-style-declaration -Wdeclaration-after-statement -fdebug-prefix-map="/home/ros/reactos"=ReactOS -gdwarf-2 -gstrict-dwarf -femit-struct-debug-detailed=none -feliminate-unused-debug-symbols -march=pentium -mtune=i686 -Werror -Wall -Wpointer-arith -Wno-char-subscripts -Wno-multichar -Wno-unused-value -Wno-maybe-uninitialized -O1 -fno-optimize-sibling-calls -fno-omit-frame-pointer -mpreferred-stack-boundary=3 -fno-set-stack-executable -Winvalid-pch -Werror=invalid-pch -Ibase/shell/progman -I../../base/shell/progman -I../../sdk/include -I../../sdk/include/psdk -I../../sdk/include/dxsdk -Isdk/include -Isdk/include/psdk -Isdk/include/dxsdk -Isdk/include/ddk -Isdk/include/reactos -I../../sdk/include/crt -I../../sdk/include/ddk -I../../sdk/include/ndk -I../../sdk/include/reactos -I../../sdk/include/reactos/libs -MMD -MT base/shell/progman/progman_pch.h.gch -MF base/shell/progman/progman_pch.h.gch.d -o base/shell/progman/progman_pch.h.gch -c ../../base/shell/progman/progman.h
../../base/shell/progman/progman.h:35:9: error: #pragma once in main file [-Werror]
cc1: all warnings being treated as errors
[206/1104] Linking C executable base/shell/cmd/cmd.exe
ninja: build stopped: subcommand failed.